Dear Stable,
Lee pointed out issue found by syscaller [0] hitting BUG in prog array map poke update in prog_array_map_poke_run function due to error value returned from bpf_arch_text_poke function.
There's race window where bpf_arch_text_poke can fail due to missing bpf program kallsym symbols, which is accounted for with check for -EINVAL in that BUG_ON call.
The problem is that in such case we won't update the tail call jump and cause imbalance for the next tail call update check which will fail with -EBUSY in bpf_arch_text_poke.
I'm hitting following race during the program load:
CPU 0 CPU 1
bpf_prog_load bpf_check do_misc_fixups prog_array_map_poke_track
map_update_elem bpf_fd_array_map_update_elem prog_array_map_poke_run bpf_arch_text_poke returns -EINVAL bpf_prog_kallsyms_addAfter bpf_arch_text_poke (CPU 1) fails to update the tail call jump, the next poke update fails on expected jump instruction check in bpf_arch_text_poke with -EBUSY and triggers the BUG_ON in prog_array_map_poke_run.
Similar race exists on the program unload.
Fixing this by moving the update to bpf_arch_poke_desc_update function which makes sure we call __bpf_arch_text_poke that skips the bpf address check.
Each architecture has slightly different approach wrt looking up bpf address in bpf_arch_text_poke, so instead of splitting the function or adding new 'checkip' argument in previous version, it seems best to move the whole map_poke_run update as arch specific code.
[0] https://syzkaller.appspot.com/bug?extid=97a4fe20470e9bc30810
Cc: Lee Jones lee@kernel.org Cc: Maciej Fijalkowski maciej.fijalkowski@intel.com Fixes: ebf7d1f508a7 ("bpf, x64: rework pro/epilogue and tailcall handling in JIT") Reported-by: syzbot+97a4fe20470e9bc30810@syzkaller.appspotmail.com Acked-by: Yonghong Song yonghong.song@linux.dev Signed-off-by: Jiri Olsa jolsa@kernel.org
arch/x86/net/bpf_jit_comp.c | 46 +++++++++++++++++++++++++++++ include/linux/bpf.h | 3 ++ kernel/bpf/arraymap.c | 58 +++++++------------------------------ 3 files changed, 59 insertions(+), 48 deletions(-)
Please could we have this backported?
Guided by the Fixes: tag.
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index 8c10d9abc239..e89e415aa743 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -3025,3 +3025,49 @@ void arch_bpf_stack_walk(bool (*consume_fn)(void *cookie, u64 ip, u64 sp, u64 bp #endif WARN(1, "verification of programs using bpf_throw should have failed\n"); }
+void bpf_arch_poke_desc_update(struct bpf_jit_poke_descriptor *poke,
struct bpf_prog *new, struct bpf_prog *old)+{
- u8 *old_addr, *new_addr, *old_bypass_addr;
- int ret;
- old_bypass_addr = old ? NULL : poke->bypass_addr;
- old_addr = old ? (u8 *)old->bpf_func + poke->adj_off : NULL;
- new_addr = new ? (u8 *)new->bpf_func + poke->adj_off : NULL;
- /*
* On program loading or teardown, the program's kallsym entry* might not be in place, so we use __bpf_arch_text_poke to skip* the kallsyms check.*/- if (new) {
ret = __bpf_arch_text_poke(poke->tailcall_target,BPF_MOD_JUMP,old_addr, new_addr);BUG_ON(ret < 0);if (!old) {ret = __bpf_arch_text_poke(poke->tailcall_bypass,BPF_MOD_JUMP,poke->bypass_addr,NULL);BUG_ON(ret < 0);}- } else {
ret = __bpf_arch_text_poke(poke->tailcall_bypass,BPF_MOD_JUMP,old_bypass_addr,poke->bypass_addr);BUG_ON(ret < 0);/* let other CPUs finish the execution of program* so that it will not possible to expose them* to invalid nop, stack unwind, nop state*/if (!ret)synchronize_rcu();ret = __bpf_arch_text_poke(poke->tailcall_target,BPF_MOD_JUMP,old_addr, NULL);BUG_ON(ret < 0);- }
+} diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 6762dac3ef76..cff5bb08820e 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -3175,6 +3175,9 @@ enum bpf_text_poke_type { int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type t, void *addr1, void *addr2); +void bpf_arch_poke_desc_update(struct bpf_jit_poke_descriptor *poke,
struct bpf_prog *new, struct bpf_prog *old);void *bpf_arch_text_copy(void *dst, void *src, size_t len); int bpf_arch_text_invalidate(void *dst, size_t len); diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c index 2058e89b5ddd..c85ff9162a5c 100644 --- a/kernel/bpf/arraymap.c +++ b/kernel/bpf/arraymap.c @@ -1012,11 +1012,16 @@ static void prog_array_map_poke_untrack(struct bpf_map *map, mutex_unlock(&aux->poke_mutex); } +void __weak bpf_arch_poke_desc_update(struct bpf_jit_poke_descriptor *poke,
struct bpf_prog *new, struct bpf_prog *old)+{
- WARN_ON_ONCE(1);
+}
static void prog_array_map_poke_run(struct bpf_map *map, u32 key, struct bpf_prog *old, struct bpf_prog *new) {
- u8 *old_addr, *new_addr, *old_bypass_addr; struct prog_poke_elem *elem; struct bpf_array_aux *aux;
@@ -1025,7 +1030,7 @@ static void prog_array_map_poke_run(struct bpf_map *map, u32 key, list_for_each_entry(elem, &aux->poke_progs, list) { struct bpf_jit_poke_descriptor *poke;
int i, ret;
int i;for (i = 0; i < elem->aux->size_poke_tab; i++) { poke = &elem->aux->poke_tab[i]; @@ -1044,21 +1049,10 @@ static void prog_array_map_poke_run(struct bpf_map *map, u32 key, * activated, so tail call updates can arrive from here * while JIT is still finishing its final fixup for * non-activated poke entries.
* 3) On program teardown, the program's kallsym entry gets* removed out of RCU callback, but we can only untrack* from sleepable context, therefore bpf_arch_text_poke()* might not see that this is in BPF text section and* bails out with -EINVAL. As these are unreachable since* RCU grace period already passed, we simply skip them.* 4) Also programs reaching refcount of zero while patching
* 3) Also programs reaching refcount of zero while patching * is in progress is okay since we're protected under * poke_mutex and untrack the programs before the JIT
* buffer is freed. When we're still in the middle of* patching and suddenly kallsyms entry of the program* gets evicted, we just skip the rest which is fine due* to point 3).* 5) Any other error happening below from bpf_arch_text_poke()* is a unexpected bug.
* buffer is freed. */ if (!READ_ONCE(poke->tailcall_target_stable)) continue;@@ -1068,39 +1062,7 @@ static void prog_array_map_poke_run(struct bpf_map *map, u32 key, poke->tail_call.key != key) continue;
old_bypass_addr = old ? NULL : poke->bypass_addr;old_addr = old ? (u8 *)old->bpf_func + poke->adj_off : NULL;new_addr = new ? (u8 *)new->bpf_func + poke->adj_off : NULL;if (new) {ret = bpf_arch_text_poke(poke->tailcall_target,BPF_MOD_JUMP,old_addr, new_addr);BUG_ON(ret < 0 && ret != -EINVAL);if (!old) {ret = bpf_arch_text_poke(poke->tailcall_bypass,BPF_MOD_JUMP,poke->bypass_addr,NULL);BUG_ON(ret < 0 && ret != -EINVAL);}} else {ret = bpf_arch_text_poke(poke->tailcall_bypass,BPF_MOD_JUMP,old_bypass_addr,poke->bypass_addr);BUG_ON(ret < 0 && ret != -EINVAL);/* let other CPUs finish the execution of program* so that it will not possible to expose them* to invalid nop, stack unwind, nop state*/if (!ret)synchronize_rcu();ret = bpf_arch_text_poke(poke->tailcall_target,BPF_MOD_JUMP,old_addr, NULL);BUG_ON(ret < 0 && ret != -EINVAL);}
bpf_arch_poke_desc_update(poke, new, old);}
2.43.0
On Thu, Dec 21, 2023 at 09:07:45AM +0000, Lee Jones wrote:
Dear Stable,
Lee pointed out issue found by syscaller [0] hitting BUG in prog array map poke update in prog_array_map_poke_run function due to error value returned from bpf_arch_text_poke function.
There's race window where bpf_arch_text_poke can fail due to missing bpf program kallsym symbols, which is accounted for with check for -EINVAL in that BUG_ON call.
The problem is that in such case we won't update the tail call jump and cause imbalance for the next tail call update check which will fail with -EBUSY in bpf_arch_text_poke.
I'm hitting following race during the program load:
CPU 0 CPU 1
bpf_prog_load bpf_check do_misc_fixups prog_array_map_poke_track
map_update_elem bpf_fd_array_map_update_elem prog_array_map_poke_run bpf_arch_text_poke returns -EINVAL bpf_prog_kallsyms_addAfter bpf_arch_text_poke (CPU 1) fails to update the tail call jump, the next poke update fails on expected jump instruction check in bpf_arch_text_poke with -EBUSY and triggers the BUG_ON in prog_array_map_poke_run.
Similar race exists on the program unload.
Fixing this by moving the update to bpf_arch_poke_desc_update function which makes sure we call __bpf_arch_text_poke that skips the bpf address check.
Each architecture has slightly different approach wrt looking up bpf address in bpf_arch_text_poke, so instead of splitting the function or adding new 'checkip' argument in previous version, it seems best to move the whole map_poke_run update as arch specific code.
[0] https://syzkaller.appspot.com/bug?extid=97a4fe20470e9bc30810
Cc: Lee Jones lee@kernel.org Cc: Maciej Fijalkowski maciej.fijalkowski@intel.com Fixes: ebf7d1f508a7 ("bpf, x64: rework pro/epilogue and tailcall handling in JIT") Reported-by: syzbot+97a4fe20470e9bc30810@syzkaller.appspotmail.com Acked-by: Yonghong Song yonghong.song@linux.dev Signed-off-by: Jiri Olsa jolsa@kernel.org
arch/x86/net/bpf_jit_comp.c | 46 +++++++++++++++++++++++++++++ include/linux/bpf.h | 3 ++ kernel/bpf/arraymap.c | 58 +++++++------------------------------ 3 files changed, 59 insertions(+), 48 deletions(-)
Please could we have this backported?
Guided by the Fixes: tag.
<formletter>
This is not the correct way to submit patches for inclusion in the stable kernel tree. Please read: https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html for how to do this properly.
</formletter>
On Thu, 21 Dec 2023, Greg KH wrote:
On Thu, Dec 21, 2023 at 09:07:45AM +0000, Lee Jones wrote:
Dear Stable,
Lee pointed out issue found by syscaller [0] hitting BUG in prog array map poke update in prog_array_map_poke_run function due to error value returned from bpf_arch_text_poke function.
There's race window where bpf_arch_text_poke can fail due to missing bpf program kallsym symbols, which is accounted for with check for -EINVAL in that BUG_ON call.
The problem is that in such case we won't update the tail call jump and cause imbalance for the next tail call update check which will fail with -EBUSY in bpf_arch_text_poke.
I'm hitting following race during the program load:
CPU 0 CPU 1
bpf_prog_load bpf_check do_misc_fixups prog_array_map_poke_track
map_update_elem bpf_fd_array_map_update_elem prog_array_map_poke_run bpf_arch_text_poke returns -EINVAL bpf_prog_kallsyms_addAfter bpf_arch_text_poke (CPU 1) fails to update the tail call jump, the next poke update fails on expected jump instruction check in bpf_arch_text_poke with -EBUSY and triggers the BUG_ON in prog_array_map_poke_run.
Similar race exists on the program unload.
Fixing this by moving the update to bpf_arch_poke_desc_update function which makes sure we call __bpf_arch_text_poke that skips the bpf address check.
Each architecture has slightly different approach wrt looking up bpf address in bpf_arch_text_poke, so instead of splitting the function or adding new 'checkip' argument in previous version, it seems best to move the whole map_poke_run update as arch specific code.
[0] https://syzkaller.appspot.com/bug?extid=97a4fe20470e9bc30810
Cc: Lee Jones lee@kernel.org Cc: Maciej Fijalkowski maciej.fijalkowski@intel.com Fixes: ebf7d1f508a7 ("bpf, x64: rework pro/epilogue and tailcall handling in JIT") Reported-by: syzbot+97a4fe20470e9bc30810@syzkaller.appspotmail.com Acked-by: Yonghong Song yonghong.song@linux.dev Signed-off-by: Jiri Olsa jolsa@kernel.org
arch/x86/net/bpf_jit_comp.c | 46 +++++++++++++++++++++++++++++ include/linux/bpf.h | 3 ++ kernel/bpf/arraymap.c | 58 +++++++------------------------------ 3 files changed, 59 insertions(+), 48 deletions(-)
Please could we have this backported?
Guided by the Fixes: tag.
<formletter>
This is not the correct way to submit patches for inclusion in the stable kernel tree. Please read: https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html for how to do this properly.
</formletter>
Apologies.
Commit ID: 4b7de801606e504e69689df71475d27e35336fb3 Subject: bpf: Fix prog_array_map_poke_run map poke update Reason: Fixes a race condition in BPF. Versions: linux-5.10.y+, as specified by the Fixes: tag above
Thanks.
On Thu, Dec 21, 2023 at 09:55:22AM +0000, Lee Jones wrote:
On Thu, 21 Dec 2023, Greg KH wrote:
On Thu, Dec 21, 2023 at 09:07:45AM +0000, Lee Jones wrote:
Dear Stable,
Lee pointed out issue found by syscaller [0] hitting BUG in prog array map poke update in prog_array_map_poke_run function due to error value returned from bpf_arch_text_poke function.
There's race window where bpf_arch_text_poke can fail due to missing bpf program kallsym symbols, which is accounted for with check for -EINVAL in that BUG_ON call.
The problem is that in such case we won't update the tail call jump and cause imbalance for the next tail call update check which will fail with -EBUSY in bpf_arch_text_poke.
I'm hitting following race during the program load:
CPU 0 CPU 1
bpf_prog_load bpf_check do_misc_fixups prog_array_map_poke_track
map_update_elem bpf_fd_array_map_update_elem prog_array_map_poke_run bpf_arch_text_poke returns -EINVAL bpf_prog_kallsyms_addAfter bpf_arch_text_poke (CPU 1) fails to update the tail call jump, the next poke update fails on expected jump instruction check in bpf_arch_text_poke with -EBUSY and triggers the BUG_ON in prog_array_map_poke_run.
Similar race exists on the program unload.
Fixing this by moving the update to bpf_arch_poke_desc_update function which makes sure we call __bpf_arch_text_poke that skips the bpf address check.
Each architecture has slightly different approach wrt looking up bpf address in bpf_arch_text_poke, so instead of splitting the function or adding new 'checkip' argument in previous version, it seems best to move the whole map_poke_run update as arch specific code.
[0] https://syzkaller.appspot.com/bug?extid=97a4fe20470e9bc30810
Cc: Lee Jones lee@kernel.org Cc: Maciej Fijalkowski maciej.fijalkowski@intel.com Fixes: ebf7d1f508a7 ("bpf, x64: rework pro/epilogue and tailcall handling in JIT") Reported-by: syzbot+97a4fe20470e9bc30810@syzkaller.appspotmail.com Acked-by: Yonghong Song yonghong.song@linux.dev Signed-off-by: Jiri Olsa jolsa@kernel.org
arch/x86/net/bpf_jit_comp.c | 46 +++++++++++++++++++++++++++++ include/linux/bpf.h | 3 ++ kernel/bpf/arraymap.c | 58 +++++++------------------------------ 3 files changed, 59 insertions(+), 48 deletions(-)
Please could we have this backported?
Guided by the Fixes: tag.
<formletter>
This is not the correct way to submit patches for inclusion in the stable kernel tree. Please read: https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html for how to do this properly.
</formletter>
Apologies.
Commit ID: 4b7de801606e504e69689df71475d27e35336fb3 Subject: bpf: Fix prog_array_map_poke_run map poke update Reason: Fixes a race condition in BPF. Versions: linux-5.10.y+, as specified by the Fixes: tag above
Did not apply to 5.10.y or 5.15.y, so if you need/want it there, we will need a working backport that has been tested. Other trees it's now queued up for.
BPF developers, please remember, just adding a "Fixes:" tag does NOT guarantee that any patch will be backported to any stable kernel, you MUST add a "cc: stable@..." tag to the patch if you wish to have it automatically backported.
thanks,
greg k-h
On Thu, 21 Dec 2023, Greg KH wrote:
On Thu, Dec 21, 2023 at 09:55:22AM +0000, Lee Jones wrote:
On Thu, 21 Dec 2023, Greg KH wrote:
On Thu, Dec 21, 2023 at 09:07:45AM +0000, Lee Jones wrote:
Dear Stable,
Lee pointed out issue found by syscaller [0] hitting BUG in prog array map poke update in prog_array_map_poke_run function due to error value returned from bpf_arch_text_poke function.
There's race window where bpf_arch_text_poke can fail due to missing bpf program kallsym symbols, which is accounted for with check for -EINVAL in that BUG_ON call.
The problem is that in such case we won't update the tail call jump and cause imbalance for the next tail call update check which will fail with -EBUSY in bpf_arch_text_poke.
I'm hitting following race during the program load:
CPU 0 CPU 1
bpf_prog_load bpf_check do_misc_fixups prog_array_map_poke_track
map_update_elem bpf_fd_array_map_update_elem prog_array_map_poke_run bpf_arch_text_poke returns -EINVAL bpf_prog_kallsyms_addAfter bpf_arch_text_poke (CPU 1) fails to update the tail call jump, the next poke update fails on expected jump instruction check in bpf_arch_text_poke with -EBUSY and triggers the BUG_ON in prog_array_map_poke_run.
Similar race exists on the program unload.
Fixing this by moving the update to bpf_arch_poke_desc_update function which makes sure we call __bpf_arch_text_poke that skips the bpf address check.
Each architecture has slightly different approach wrt looking up bpf address in bpf_arch_text_poke, so instead of splitting the function or adding new 'checkip' argument in previous version, it seems best to move the whole map_poke_run update as arch specific code.
[0] https://syzkaller.appspot.com/bug?extid=97a4fe20470e9bc30810
Cc: Lee Jones lee@kernel.org Cc: Maciej Fijalkowski maciej.fijalkowski@intel.com Fixes: ebf7d1f508a7 ("bpf, x64: rework pro/epilogue and tailcall handling in JIT") Reported-by: syzbot+97a4fe20470e9bc30810@syzkaller.appspotmail.com Acked-by: Yonghong Song yonghong.song@linux.dev Signed-off-by: Jiri Olsa jolsa@kernel.org
arch/x86/net/bpf_jit_comp.c | 46 +++++++++++++++++++++++++++++ include/linux/bpf.h | 3 ++ kernel/bpf/arraymap.c | 58 +++++++------------------------------ 3 files changed, 59 insertions(+), 48 deletions(-)
Please could we have this backported?
Guided by the Fixes: tag.
<formletter>
This is not the correct way to submit patches for inclusion in the stable kernel tree. Please read: https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html for how to do this properly.
</formletter>
Apologies.
Commit ID: 4b7de801606e504e69689df71475d27e35336fb3 Subject: bpf: Fix prog_array_map_poke_run map poke update Reason: Fixes a race condition in BPF. Versions: linux-5.10.y+, as specified by the Fixes: tag above
Did not apply to 5.10.y or 5.15.y, so if you need/want it there, we will need a working backport that has been tested. Other trees it's now queued up for.
Thank you.
BPF developers, please remember, just adding a "Fixes:" tag does NOT guarantee that any patch will be backported to any stable kernel, you MUST add a "cc: stable@..." tag to the patch if you wish to have it automatically backported.
On Thu, Dec 21, 2023 at 10:17:44AM +0000, Lee Jones wrote:
On Thu, 21 Dec 2023, Greg KH wrote:
On Thu, Dec 21, 2023 at 09:55:22AM +0000, Lee Jones wrote:
On Thu, 21 Dec 2023, Greg KH wrote:
On Thu, Dec 21, 2023 at 09:07:45AM +0000, Lee Jones wrote:
Dear Stable,
Lee pointed out issue found by syscaller [0] hitting BUG in prog array map poke update in prog_array_map_poke_run function due to error value returned from bpf_arch_text_poke function.
There's race window where bpf_arch_text_poke can fail due to missing bpf program kallsym symbols, which is accounted for with check for -EINVAL in that BUG_ON call.
The problem is that in such case we won't update the tail call jump and cause imbalance for the next tail call update check which will fail with -EBUSY in bpf_arch_text_poke.
I'm hitting following race during the program load:
CPU 0 CPU 1
bpf_prog_load bpf_check do_misc_fixups prog_array_map_poke_track
map_update_elem bpf_fd_array_map_update_elem prog_array_map_poke_run bpf_arch_text_poke returns -EINVAL bpf_prog_kallsyms_addAfter bpf_arch_text_poke (CPU 1) fails to update the tail call jump, the next poke update fails on expected jump instruction check in bpf_arch_text_poke with -EBUSY and triggers the BUG_ON in prog_array_map_poke_run.
Similar race exists on the program unload.
Fixing this by moving the update to bpf_arch_poke_desc_update function which makes sure we call __bpf_arch_text_poke that skips the bpf address check.
Each architecture has slightly different approach wrt looking up bpf address in bpf_arch_text_poke, so instead of splitting the function or adding new 'checkip' argument in previous version, it seems best to move the whole map_poke_run update as arch specific code.
[0] https://syzkaller.appspot.com/bug?extid=97a4fe20470e9bc30810
Cc: Lee Jones lee@kernel.org Cc: Maciej Fijalkowski maciej.fijalkowski@intel.com Fixes: ebf7d1f508a7 ("bpf, x64: rework pro/epilogue and tailcall handling in JIT") Reported-by: syzbot+97a4fe20470e9bc30810@syzkaller.appspotmail.com Acked-by: Yonghong Song yonghong.song@linux.dev Signed-off-by: Jiri Olsa jolsa@kernel.org
arch/x86/net/bpf_jit_comp.c | 46 +++++++++++++++++++++++++++++ include/linux/bpf.h | 3 ++ kernel/bpf/arraymap.c | 58 +++++++------------------------------ 3 files changed, 59 insertions(+), 48 deletions(-)
Please could we have this backported?
Guided by the Fixes: tag.
<formletter>
This is not the correct way to submit patches for inclusion in the stable kernel tree. Please read: https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html for how to do this properly.
</formletter>
Apologies.
Commit ID: 4b7de801606e504e69689df71475d27e35336fb3 Subject: bpf: Fix prog_array_map_poke_run map poke update Reason: Fixes a race condition in BPF. Versions: linux-5.10.y+, as specified by the Fixes: tag above
Did not apply to 5.10.y or 5.15.y, so if you need/want it there, we will need a working backport that has been tested. Other trees it's now queued up for.
Thank you.
please let me know if you need any help with that, I can check on that
jirka
BPF developers, please remember, just adding a "Fixes:" tag does NOT guarantee that any patch will be backported to any stable kernel, you MUST add a "cc: stable@..." tag to the patch if you wish to have it automatically backported.
-- Lee Jones [李琼斯]
On Thu, 21 Dec 2023, Jiri Olsa wrote:
On Thu, Dec 21, 2023 at 10:17:44AM +0000, Lee Jones wrote:
On Thu, 21 Dec 2023, Greg KH wrote:
On Thu, Dec 21, 2023 at 09:55:22AM +0000, Lee Jones wrote:
On Thu, 21 Dec 2023, Greg KH wrote:
On Thu, Dec 21, 2023 at 09:07:45AM +0000, Lee Jones wrote:
Dear Stable,
> Lee pointed out issue found by syscaller [0] hitting BUG in prog array > map poke update in prog_array_map_poke_run function due to error value > returned from bpf_arch_text_poke function. > > There's race window where bpf_arch_text_poke can fail due to missing > bpf program kallsym symbols, which is accounted for with check for > -EINVAL in that BUG_ON call. > > The problem is that in such case we won't update the tail call jump > and cause imbalance for the next tail call update check which will > fail with -EBUSY in bpf_arch_text_poke. > > I'm hitting following race during the program load: > > CPU 0 CPU 1 > > bpf_prog_load > bpf_check > do_misc_fixups > prog_array_map_poke_track > > map_update_elem > bpf_fd_array_map_update_elem > prog_array_map_poke_run > > bpf_arch_text_poke returns -EINVAL > > bpf_prog_kallsyms_add > > After bpf_arch_text_poke (CPU 1) fails to update the tail call jump, the next > poke update fails on expected jump instruction check in bpf_arch_text_poke > with -EBUSY and triggers the BUG_ON in prog_array_map_poke_run. > > Similar race exists on the program unload. > > Fixing this by moving the update to bpf_arch_poke_desc_update function which > makes sure we call __bpf_arch_text_poke that skips the bpf address check. > > Each architecture has slightly different approach wrt looking up bpf address > in bpf_arch_text_poke, so instead of splitting the function or adding new > 'checkip' argument in previous version, it seems best to move the whole > map_poke_run update as arch specific code. > > [0] https://syzkaller.appspot.com/bug?extid=97a4fe20470e9bc30810 > > Cc: Lee Jones lee@kernel.org > Cc: Maciej Fijalkowski maciej.fijalkowski@intel.com > Fixes: ebf7d1f508a7 ("bpf, x64: rework pro/epilogue and tailcall handling in JIT") > Reported-by: syzbot+97a4fe20470e9bc30810@syzkaller.appspotmail.com > Acked-by: Yonghong Song yonghong.song@linux.dev > Signed-off-by: Jiri Olsa jolsa@kernel.org > --- > arch/x86/net/bpf_jit_comp.c | 46 +++++++++++++++++++++++++++++ > include/linux/bpf.h | 3 ++ > kernel/bpf/arraymap.c | 58 +++++++------------------------------ > 3 files changed, 59 insertions(+), 48 deletions(-)
Please could we have this backported?
Guided by the Fixes: tag.
<formletter>
This is not the correct way to submit patches for inclusion in the stable kernel tree. Please read: https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html for how to do this properly.
</formletter>
Apologies.
Commit ID: 4b7de801606e504e69689df71475d27e35336fb3 Subject: bpf: Fix prog_array_map_poke_run map poke update Reason: Fixes a race condition in BPF. Versions: linux-5.10.y+, as specified by the Fixes: tag above
Did not apply to 5.10.y or 5.15.y, so if you need/want it there, we will need a working backport that has been tested. Other trees it's now queued up for.
Thank you.
please let me know if you need any help with that, I can check on that
I absolutely do. I have no way to test BPF.
linux-stable-mirror@lists.linaro.org
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Greg KH -
Jiri Olsa -
Lee Jones