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[PATCH 086/103] binder: fix use-after-free in binder_transaction()

by micky387

From: Todd Kjos <tkjos(a)android.com> User-space normally keeps the node alive when creating a transaction since it has a reference to the target. The local strong ref keeps it alive if the sending process dies before the target process processes the transaction. If the source process is malicious or has a reference counting bug, this can fail. In this case, when we attempt to decrement the node in the failure path, the node has already been freed. This is fixed by taking a tmpref on the node while constructing the transaction. To avoid re-acquiring the node lock and inner proc lock to increment the proc's tmpref, a helper is used that does the ref increments on both the node and proc. Signed-off-by: Todd Kjos <tkjos(a)google.com> Cc: stable <stable(a)vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> --- drivers/android/binder.c | 93 ++++++++++++++++++++++++++++++++++-------------- 1 file changed, 66 insertions(+), 27 deletions(-) diff --git a/drivers/android/binder.c b/drivers/android/binder.c index 3f9d702..fa23e45 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -2582,6 +2582,48 @@ static bool binder_proc_transaction(struct binder_transaction *t, return true; } +/** + * binder_get_node_refs_for_txn() - Get required refs on node for txn + * @node: struct binder_node for which to get refs + * @proc: returns @node->proc if valid + * @error: if no @proc then returns BR_DEAD_REPLY + * + * User-space normally keeps the node alive when creating a transaction + * since it has a reference to the target. The local strong ref keeps it + * alive if the sending process dies before the target process processes + * the transaction. If the source process is malicious or has a reference + * counting bug, relying on the local strong ref can fail. + * + * Since user-space can cause the local strong ref to go away, we also take + * a tmpref on the node to ensure it survives while we are constructing + * the transaction. We also need a tmpref on the proc while we are + * constructing the transaction, so we take that here as well. + * + * Return: The target_node with refs taken or NULL if no @node->proc is NULL. + * Also sets @proc if valid. If the @node->proc is NULL indicating that the + * target proc has died, @error is set to BR_DEAD_REPLY + */ +static struct binder_node *binder_get_node_refs_for_txn( + struct binder_node *node, + struct binder_proc **procp, + uint32_t *error) +{ + struct binder_node *target_node = NULL; + + binder_node_inner_lock(node); + if (node->proc) { + target_node = node; + binder_inc_node_nilocked(node, 1, 0, NULL); + binder_inc_node_tmpref_ilocked(node); + node->proc->tmp_ref++; + *procp = node->proc; + } else + *error = BR_DEAD_REPLY; + binder_node_inner_unlock(node); + + return target_node; +} + static void binder_transaction(struct binder_proc *proc, struct binder_thread *thread, struct binder_transaction_data *tr, int reply, @@ -2685,43 +2727,35 @@ static void binder_transaction(struct binder_proc *proc, ref = binder_get_ref_olocked(proc, tr->target.handle, true); if (ref) { - binder_inc_node(ref->node, 1, 0, NULL); - target_node = ref->node; - } - binder_proc_unlock(proc); - if (target_node == NULL) { + target_node = binder_get_node_refs_for_txn( + ref->node, &target_proc, + &return_error); + } else { binder_user_error("%d:%d got transaction to invalid handle\n", - proc->pid, thread->pid); + proc->pid, thread->pid); return_error = BR_FAILED_REPLY; - return_error_param = -EINVAL; - return_error_line = __LINE__; - goto err_invalid_target_handle; } + binder_proc_unlock(proc); } else { mutex_lock(&context->context_mgr_node_lock); target_node = context->binder_context_mgr_node; - if (target_node == NULL) { + if (target_node) + target_node = binder_get_node_refs_for_txn( + target_node, &target_proc, + &return_error); + else return_error = BR_DEAD_REPLY; - mutex_unlock(&context->context_mgr_node_lock); - return_error_line = __LINE__; - goto err_no_context_mgr_node; - } - binder_inc_node(target_node, 1, 0, NULL); mutex_unlock(&context->context_mgr_node_lock); } - e->to_node = target_node->debug_id; - binder_node_lock(target_node); - target_proc = target_node->proc; - if (target_proc == NULL) { - binder_node_unlock(target_node); - return_error = BR_DEAD_REPLY; + if (!target_node) { + /* + * return_error is set above + */ + return_error_param = -EINVAL; return_error_line = __LINE__; goto err_dead_binder; } - binder_inner_proc_lock(target_proc); - target_proc->tmp_ref++; - binder_inner_proc_unlock(target_proc); - binder_node_unlock(target_node); + e->to_node = target_node->debug_id; if (security_binder_transaction(proc->tsk, target_proc->tsk) < 0) { return_error = BR_FAILED_REPLY; @@ -3071,6 +3105,8 @@ static void binder_transaction(struct binder_proc *proc, if (target_thread) binder_thread_dec_tmpref(target_thread); binder_proc_dec_tmpref(target_proc); + if (target_node) + binder_dec_node_tmpref(target_node); /* * write barrier to synchronize with initialization * of log entry @@ -3089,6 +3125,8 @@ err_bad_parent: err_copy_data_failed: trace_binder_transaction_failed_buffer_release(t->buffer); binder_transaction_buffer_release(target_proc, t->buffer, offp); + if (target_node) + binder_dec_node_tmpref(target_node); target_node = NULL; t->buffer->transaction = NULL; binder_alloc_free_buf(&target_proc->alloc, t->buffer); @@ -3103,13 +3141,14 @@ err_bad_call_stack: err_empty_call_stack: err_dead_binder: err_invalid_target_handle: -err_no_context_mgr_node: if (target_thread) binder_thread_dec_tmpref(target_thread); if (target_proc) binder_proc_dec_tmpref(target_proc); - if (target_node) + if (target_node) { binder_dec_node(target_node, 1, 0); + binder_dec_node_tmpref(target_node); + } binder_debug(BINDER_DEBUG_FAILED_TRANSACTION, "%d:%d transaction failed %d/%d, size %lld-%lld line %d\n", -- 2.7.4

7 years, 4 months

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[PATCH 073/103] binder: free memory on error

by micky387

From: Christian Brauner <christian.brauner(a)ubuntu.com> On binder_init() the devices string is duplicated and smashed into individual device names which are passed along. However, the original duplicated string wasn't freed in case binder_init() failed. Let's free it on error. Signed-off-by: Christian Brauner <christian.brauner(a)ubuntu.com> Cc: stable <stable(a)vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> --- drivers/android/binder.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/android/binder.c b/drivers/android/binder.c index c40cd0c..ddd4235 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -5236,7 +5236,7 @@ static int __init init_binder_device(const char *name) static int __init binder_init(void) { int ret; - char *device_name, *device_names; + char *device_name, *device_names, *device_tmp; struct binder_device *device; struct hlist_node *tmp; @@ -5287,7 +5287,8 @@ static int __init binder_init(void) } strcpy(device_names, binder_devices_param); - while ((device_name = strsep(&device_names, ","))) { + device_tmp = device_names; + while ((device_name = strsep(&device_tmp, ","))) { ret = init_binder_device(device_name); if (ret) goto err_init_binder_device_failed; @@ -5301,6 +5302,9 @@ err_init_binder_device_failed: hlist_del(&device->hlist); kfree(device); } + + kfree(device_names); + err_alloc_device_names_failed: debugfs_remove_recursive(binder_debugfs_dir_entry_root); -- 2.7.4

7 years, 4 months

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[PATCH 072/103] ANDROID: binder: add hwbinder, vndbinder to BINDER_DEVICES.

by micky387

From: Martijn Coenen <maco(a)android.com> These will be required going forward. Change-Id: I960e205e7974079313da208959794c58577bdaa9 Signed-off-by: Martijn Coenen <maco(a)android.com> Cc: stable <stable(a)vger.kernel.org> # 4.11+ Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> --- drivers/android/Kconfig | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/android/Kconfig b/drivers/android/Kconfig index 832e885..4d4cdc1a 100644 --- a/drivers/android/Kconfig +++ b/drivers/android/Kconfig @@ -22,7 +22,7 @@ config ANDROID_BINDER_IPC config ANDROID_BINDER_DEVICES string "Android Binder devices" depends on ANDROID_BINDER_IPC - default "binder,hwbinder" + default "binder,hwbinder,vndbinder" ---help--- Default value for the binder.devices parameter. -- 2.7.4

7 years, 4 months

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[PATCH 044/103] binder: use group leader instead of open thread

by micky387

From: Todd Kjos <tkjos(a)android.com> The binder allocator assumes that the thread that called binder_open will never die for the lifetime of that proc. That thread is normally the group_leader, however it may not be. Use the group_leader instead of current. Signed-off-by: Todd Kjos <tkjos(a)google.com> Cc: stable <stable(a)vger.kernel.org> # 4.4+ Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> --- drivers/android/binder.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/android/binder.c b/drivers/android/binder.c index fbe0eb9..a24ad74 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -3039,8 +3039,8 @@ static int binder_open(struct inode *nodp, struct file *filp) proc = kzalloc(sizeof(*proc), GFP_KERNEL); if (proc == NULL) return -ENOMEM; - get_task_struct(current); - proc->tsk = current; + get_task_struct(current->group_leader); + proc->tsk = current->group_leader; INIT_LIST_HEAD(&proc->todo); init_waitqueue_head(&proc->wait); proc->default_priority = task_nice(current); -- 2.7.4

7 years, 4 months

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[PATCH 034/103] binder: Use wake up hint for synchronous transactions.

by micky387

From: Riley Andrews <riandrews(a)google.com> Use wake_up_interruptible_sync() to hint to the scheduler binder transactions are synchronous wakeups. Disable preemption while waking to avoid ping-ponging on the binder lock. Signed-off-by: Todd Kjos <tkjos(a)google.com> Signed-off-by: Omprakash Dhyade <odhyade(a)codeaurora.org> Cc: stable <stable(a)vger.kernel.org> # 4.4+ Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> --- drivers/android/binder.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/android/binder.c b/drivers/android/binder.c index b51fedc..6adf0bf 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -2199,8 +2199,12 @@ static void binder_transaction(struct binder_proc *proc, list_add_tail(&t->work.entry, target_list); tcomplete->type = BINDER_WORK_TRANSACTION_COMPLETE; list_add_tail(&tcomplete->entry, &thread->todo); - if (target_wait) - wake_up_interruptible(target_wait); + if (target_wait) { + if (reply || !(t->flags & TF_ONE_WAY)) + wake_up_interruptible_sync(target_wait); + else + wake_up_interruptible(target_wait); + } return; err_translate_failed: -- 2.7.4

7 years, 4 months

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[PATCH 033/103] Revert "android: binder: Sanity check at binder ioctl"

by micky387

From: Todd Kjos <tkjos(a)android.com> This reverts commit a906d6931f3ccaf7de805643190765ddd7378e27. The patch introduced a race in the binder driver. An attempt to fix the race was submitted in "[PATCH v2] android: binder: fix dangling pointer comparison", however the conclusion in the discussion for that patch was that the original patch should be reverted. The reversion is being done as part of the fine-grained locking patchset since the patch would need to be refactored when proc->vmm_vm_mm is removed from struct binder_proc and added in the binder allocator. Signed-off-by: Todd Kjos <tkjos(a)google.com> Cc: stable <stable(a)vger.kernel.org> # 4.6+ Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> --- drivers/android/binder.c | 5 ----- 1 file changed, 5 deletions(-) diff --git a/drivers/android/binder.c b/drivers/android/binder.c index 15b263a..b51fedc 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -3246,10 +3246,6 @@ static long binder_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) /*pr_info("binder_ioctl: %d:%d %x %lx\n", proc->pid, current->pid, cmd, arg);*/ - if (unlikely(current->mm != proc->vma_vm_mm)) { - pr_err("current mm mismatch proc mm\n"); - return -EINVAL; - } trace_binder_ioctl(cmd, arg); ret = wait_event_interruptible(binder_user_error_wait, binder_stop_on_user_error < 2); @@ -3465,7 +3461,6 @@ static int binder_open(struct inode *nodp, struct file *filp) return -ENOMEM; get_task_struct(current); proc->tsk = current; - proc->vma_vm_mm = current->mm; INIT_LIST_HEAD(&proc->todo); init_waitqueue_head(&proc->wait); proc->default_priority = task_nice(current); -- 2.7.4

7 years, 4 months

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[PATCH 030/103] ANDROID: binder: add padding to binder_fd_array_object.

by micky387

From: Martijn Coenen <maco(a)android.com> binder_fd_array_object starts with a 4-byte header, followed by a few fields that are 8 bytes when ANDROID_BINDER_IPC_32BIT=N. This can cause alignment issues in a 64-bit kernel with a 32-bit userspace, as on x86_32 an 8-byte primitive may be aligned to a 4-byte address. Pad with a __u32 to fix this. Signed-off-by: Martijn Coenen <maco(a)android.com> Cc: stable <stable(a)vger.kernel.org> # 4.11+ Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> --- include/uapi/linux/android/binder.h | 2 ++ 1 file changed, 2 insertions(+) diff --git a/include/uapi/linux/android/binder.h b/include/uapi/linux/android/binder.h index 51f891f..7668b57 100644 --- a/include/uapi/linux/android/binder.h +++ b/include/uapi/linux/android/binder.h @@ -132,6 +132,7 @@ enum { /* struct binder_fd_array_object - object describing an array of fds in a buffer * @hdr: common header structure + * @pad: padding to ensure correct alignment * @num_fds: number of file descriptors in the buffer * @parent: index in offset array to buffer holding the fd array * @parent_offset: start offset of fd array in the buffer @@ -152,6 +153,7 @@ enum { */ struct binder_fd_array_object { struct binder_object_header hdr; + __u32 pad; binder_size_t num_fds; binder_size_t parent; binder_size_t parent_offset; -- 2.7.4

7 years, 4 months

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[PATCH 021/103] ANDROID: binder: Clear binder and cookie when setting handle in flat binder struct

by micky387

From: Arve Hjønnevåg <arve(a)android.com> Prevents leaking pointers between processes Signed-off-by: Arve Hjønnevåg <arve(a)android.com> Signed-off-by: Martijn Coenen <maco(a)android.com> Cc: stable <stable(a)vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> --- drivers/android/binder.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/android/binder.c b/drivers/android/binder.c index 3681759..3c71b98 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -1584,7 +1584,9 @@ static void binder_transaction(struct binder_proc *proc, fp->type = BINDER_TYPE_HANDLE; else fp->type = BINDER_TYPE_WEAK_HANDLE; + fp->binder = 0; fp->handle = ref->desc; + fp->cookie = 0; binder_inc_ref(ref, fp->type == BINDER_TYPE_HANDLE, &thread->todo); @@ -1634,7 +1636,9 @@ static void binder_transaction(struct binder_proc *proc, return_error = BR_FAILED_REPLY; goto err_binder_get_ref_for_node_failed; } + fp->binder = 0; fp->handle = new_ref->desc; + fp->cookie = 0; binder_inc_ref(new_ref, fp->type == BINDER_TYPE_HANDLE, NULL); trace_binder_transaction_ref_to_ref(t, ref, new_ref); @@ -1688,6 +1692,7 @@ static void binder_transaction(struct binder_proc *proc, binder_debug(BINDER_DEBUG_TRANSACTION, " fd %d -> %d\n", fp->handle, target_fd); /* TODO: fput? */ + fp->binder = 0; fp->handle = target_fd; } break; -- 2.7.4

7 years, 4 months

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[PATCH 020/103] ANDROID: binder: Add strong ref checks

by micky387

From: Arve Hjønnevåg <arve(a)android.com> Prevent using a binder_ref with only weak references where a strong reference is required. Signed-off-by: Arve Hjønnevåg <arve(a)android.com> Signed-off-by: Martijn Coenen <maco(a)android.com> Cc: stable <stable(a)vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> --- drivers/android/binder.c | 30 +++++++++++++++++++++--------- 1 file changed, 21 insertions(+), 9 deletions(-) diff --git a/drivers/android/binder.c b/drivers/android/binder.c index 562af94..3681759 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -1002,7 +1002,7 @@ static int binder_dec_node(struct binder_node *node, int strong, int internal) static struct binder_ref *binder_get_ref(struct binder_proc *proc, - uint32_t desc) + u32 desc, bool need_strong_ref) { struct rb_node *n = proc->refs_by_desc.rb_node; struct binder_ref *ref; @@ -1010,12 +1010,16 @@ static struct binder_ref *binder_get_ref(struct binder_proc *proc, while (n) { ref = rb_entry(n, struct binder_ref, rb_node_desc); - if (desc < ref->desc) + if (desc < ref->desc) { n = n->rb_left; - else if (desc > ref->desc) + } else if (desc > ref->desc) { n = n->rb_right; - else + } else if (need_strong_ref && !ref->strong) { + binder_user_error("tried to use weak ref as strong ref\n"); + return NULL; + } else { return ref; + } } return NULL; } @@ -1285,7 +1289,10 @@ static void binder_transaction_buffer_release(struct binder_proc *proc, } break; case BINDER_TYPE_HANDLE: case BINDER_TYPE_WEAK_HANDLE: { - struct binder_ref *ref = binder_get_ref(proc, fp->handle); + struct binder_ref *ref; + + ref = binder_get_ref(proc, fp->handle, + fp->type == BINDER_TYPE_HANDLE); if (ref == NULL) { pr_err("transaction release %d bad handle %d\n", @@ -1380,7 +1387,7 @@ static void binder_transaction(struct binder_proc *proc, if (tr->target.handle) { struct binder_ref *ref; - ref = binder_get_ref(proc, tr->target.handle); + ref = binder_get_ref(proc, tr->target.handle, true); if (ref == NULL) { binder_user_error("%d:%d got transaction to invalid handle\n", proc->pid, thread->pid); @@ -1589,7 +1596,10 @@ static void binder_transaction(struct binder_proc *proc, } break; case BINDER_TYPE_HANDLE: case BINDER_TYPE_WEAK_HANDLE: { - struct binder_ref *ref = binder_get_ref(proc, fp->handle); + struct binder_ref *ref; + + ref = binder_get_ref(proc, fp->handle, + fp->type == BINDER_TYPE_HANDLE); if (ref == NULL) { binder_user_error("%d:%d got transaction with invalid handle, %d\n", @@ -1800,7 +1810,9 @@ static int binder_thread_write(struct binder_proc *proc, ref->desc); } } else - ref = binder_get_ref(proc, target); + ref = binder_get_ref(proc, target, + cmd == BC_ACQUIRE || + cmd == BC_RELEASE); if (ref == NULL) { binder_user_error("%d:%d refcount change on invalid ref %d\n", proc->pid, thread->pid, target); @@ -1996,7 +2008,7 @@ static int binder_thread_write(struct binder_proc *proc, if (get_user(cookie, (binder_uintptr_t __user *)ptr)) return -EFAULT; ptr += sizeof(binder_uintptr_t); - ref = binder_get_ref(proc, target); + ref = binder_get_ref(proc, target, false); if (ref == NULL) { binder_user_error("%d:%d %s invalid ref %d\n", proc->pid, thread->pid, -- 2.7.4

7 years, 4 months

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[PATCH 018/103] drivers: android: correct the size of struct binder_uintptr_t for BC_DEAD_BINDER_DONE

by micky387

From: Lisa Du <cldu(a)marvell.com> There's one point was missed in the patch commit da49889deb34 ("staging: binder: Support concurrent 32 bit and 64 bit processes."). When configure BINDER_IPC_32BIT, the size of binder_uintptr_t was 32bits, but size of void * is 64bit on 64bit system. Correct it here. Signed-off-by: Lisa Du <cldu(a)marvell.com> Signed-off-by: Nicolas Boichat <drinkcat(a)chromium.org> Fixes: da49889deb34 ("staging: binder: Support concurrent 32 bit and 64 bit processes.") Cc: <stable(a)vger.kernel.org> Acked-by: Olof Johansson <olof(a)lixom.net> Signed-off-by: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> --- drivers/android/binder.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/android/binder.c b/drivers/android/binder.c index 796301a..16288e7 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -2081,7 +2081,7 @@ static int binder_thread_write(struct binder_proc *proc, if (get_user(cookie, (binder_uintptr_t __user *)ptr)) return -EFAULT; - ptr += sizeof(void *); + ptr += sizeof(cookie); list_for_each_entry(w, &proc->delivered_death, entry) { struct binder_ref_death *tmp_death = container_of(w, struct binder_ref_death, work); -- 2.7.4

7 years, 4 months

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