For some odd reason 5.10 kernel series doesn't compile with a newer
toolchain since 2025-02-09:
2025-02-09T17:32:07.7991299Z GEN .version
2025-02-09T17:32:07.8270062Z CHK include/generated/compile.h
2025-02-09T17:32:07.8540777Z LD vmlinux.o
2025-02-09T17:32:11.7210899Z MODPOST vmlinux.symvers
2025-02-09T17:32:12.0869599Z MODINFO modules.builtin.modinfo
2025-02-09T17:32:12.1403022Z GEN modules.builtin
2025-02-09T17:32:12.1475659Z LD .tmp_vmlinux.btf
2025-02-09T17:32:19.6117204Z BTF .btf.vmlinux.bin.o
2025-02-09T17:32:31.2916650Z LD .tmp_vmlinux.kallsyms1
2025-02-09T17:32:34.8731104Z KSYMS .tmp_vmlinux.kallsyms1.S
2025-02-09T17:32:35.4910608Z AS .tmp_vmlinux.kallsyms1.o
2025-02-09T17:32:35.9662538Z LD .tmp_vmlinux.kallsyms2
2025-02-09T17:32:39.2595984Z KSYMS .tmp_vmlinux.kallsyms2.S
2025-02-09T17:32:39.8802028Z AS .tmp_vmlinux.kallsyms2.o
2025-02-09T17:32:40.3659440Z LD vmlinux
2025-02-09T17:32:48.0031558Z BTFIDS vmlinux
2025-02-09T17:32:48.0143553Z FAILED unresolved symbol filp_close
2025-02-09T17:32:48.5019928Z make: *** [Makefile:1207: vmlinux] Error 255
2025-02-09T17:32:48.5061241Z ==> ERROR: A failure occurred in build().
5.10.234 built fine couple of days ago with the older one. There were
slight changes made. 5.4 and 5.15 still compile.
Wonder what might be missing here ...
--
Best, Philip
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DCCP sockets in DCCP_REQUESTING state do not check the sequence number
or acknowledgment number for incoming Reset, CloseReq, and Close packets.
As a result, an attacker can send a spoofed Reset packet while the client
is in the requesting state. The client will accept the packet without
verification and immediately close the connection, causing a denial of
service (DoS) attack.
This patch moves the processing of Reset, Close, and CloseReq packets
into dccp_rcv_request_sent_state_process() and validates the ack number
before accepting them.
This fix should apply to stable versions *only* in Linux 5.x and 6.x.
Note that DCCP was removed in Linux 6.16, so this patch is only relevant
for older versions. We tested it on Ubuntu 24.04 LTS (Linux 6.8) and
it worked as expected.
Signed-off-by: Yizhou Zhao <zhaoyz24(a)mails.tsinghua.edu.cn>
Cc: stable(a)vger.kernel.org
Signed-off-by: Yizhou Zhao <zhaoyz24(a)mails.tsinghua.edu.cn>
---
net/dccp/input.c | 54 ++++++++++++++++++++++++++++--------------------
1 file changed, 32 insertions(+), 22 deletions(-)
diff --git a/net/dccp/input.c b/net/dccp/input.c
index 2cbb757a8..0b1ffb044 100644
--- a/net/dccp/input.c
+++ b/net/dccp/input.c
@@ -397,21 +397,22 @@ static int dccp_rcv_request_sent_state_process(struct sock *sk,
* / * Response processing continues in Step 10; Reset
* processing continues in Step 9 * /
*/
+ struct dccp_sock *dp = dccp_sk(sk);
+
+ if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
+ dp->dccps_awl, dp->dccps_awh)) {
+ dccp_pr_debug("invalid ackno: S.AWL=%llu, "
+ "P.ackno=%llu, S.AWH=%llu\n",
+ (unsigned long long)dp->dccps_awl,
+ (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq,
+ (unsigned long long)dp->dccps_awh);
+ goto out_invalid_packet;
+ }
+
if (dh->dccph_type == DCCP_PKT_RESPONSE) {
const struct inet_connection_sock *icsk = inet_csk(sk);
- struct dccp_sock *dp = dccp_sk(sk);
- long tstamp = dccp_timestamp();
-
- if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
- dp->dccps_awl, dp->dccps_awh)) {
- dccp_pr_debug("invalid ackno: S.AWL=%llu, "
- "P.ackno=%llu, S.AWH=%llu\n",
- (unsigned long long)dp->dccps_awl,
- (unsigned long long)DCCP_SKB_CB(skb)->dccpd_ack_seq,
- (unsigned long long)dp->dccps_awh);
- goto out_invalid_packet;
- }
+ long tstamp = dccp_timestamp();
/*
* If option processing (Step 8) failed, return 1 here so that
* dccp_v4_do_rcv() sends a Reset. The Reset code depends on
@@ -496,6 +497,13 @@ static int dccp_rcv_request_sent_state_process(struct sock *sk,
}
dccp_send_ack(sk);
return -1;
+ } else if (dh->dccph_type == DCCP_PKT_RESET) {
+ dccp_rcv_reset(sk, skb);
+ return 0;
+ } else if (dh->dccph_type == DCCP_PKT_CLOSEREQ) {
+ return dccp_rcv_closereq(sk, skb);
+ } else if (dh->dccph_type == DCCP_PKT_CLOSE) {
+ return dccp_rcv_close(sk, skb);
}
out_invalid_packet:
@@ -658,17 +666,19 @@ int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
* Set TIMEWAIT timer
* Drop packet and return
*/
- if (dh->dccph_type == DCCP_PKT_RESET) {
- dccp_rcv_reset(sk, skb);
- return 0;
- } else if (dh->dccph_type == DCCP_PKT_CLOSEREQ) { /* Step 13 */
- if (dccp_rcv_closereq(sk, skb))
- return 0;
- goto discard;
- } else if (dh->dccph_type == DCCP_PKT_CLOSE) { /* Step 14 */
- if (dccp_rcv_close(sk, skb))
+ if (sk->sk_state != DCCP_REQUESTING) {
+ if (dh->dccph_type == DCCP_PKT_RESET) {
+ dccp_rcv_reset(sk, skb);
return 0;
- goto discard;
+ } else if (dh->dccph_type == DCCP_PKT_CLOSEREQ) { /* Step 13 */
+ if (dccp_rcv_closereq(sk, skb))
+ return 0;
+ goto discard;
+ } else if (dh->dccph_type == DCCP_PKT_CLOSE) { /* Step 14 */
+ if (dccp_rcv_close(sk, skb))
+ return 0;
+ goto discard;
+ }
}
switch (sk->sk_state) {
--
2.34.1
The patch titled
Subject: fs/proc: fix uaf in proc_readdir_de()
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
fs-proc-fix-uaf-in-proc_readdir_de.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patche…
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: Wei Yang <albinwyang(a)tencent.com>
Subject: fs/proc: fix uaf in proc_readdir_de()
Date: Sat, 25 Oct 2025 10:42:33 +0800
Pde is erased from subdir rbtree through rb_erase(), but not set the node
to EMPTY, which may result in uaf access. We should use RB_CLEAR_NODE()
set the erased node to EMPTY, then pde_subdir_next() will return NULL to
avoid uaf access.
We found an uaf issue while using stress-ng testing, need to run testcase
getdent and tun in the same time. The steps of the issue is as follows:
1) use getdent to traverse dir /proc/pid/net/dev_snmp6/, and current
pde is tun3;
2) in the [time windows] unregister netdevice tun3 and tun2, and erase
them from rbtree. erase tun3 first, and then erase tun2. the
pde(tun2) will be released to slab;
3) continue to getdent process, then pde_subdir_next() will return
pde(tun2) which is released, it will case uaf access.
CPU 0 | CPU 1
----------------------------------------------------------------------------------------------
traverse dir /proc/pid/net/dev_snmp6/ | unregister_netdevice(tun->dev) //tun3 tun2
sys_getdents64() |
iterate_dir() |
proc_readdir() |
proc_readdir_de() | snmp6_unregister_dev()
pde_get(de); | proc_remove()
read_unlock(&proc_subdir_lock); | remove_proc_subtree()
| write_lock(&proc_subdir_lock);
[time window] | rb_erase(&root->subdir_node, &parent->subdir);
| write_unlock(&proc_subdir_lock);
read_lock(&proc_subdir_lock); |
next = pde_subdir_next(de); |
pde_put(de); |
de = next; //UAF |
rbtree of dev_snmp6
|
pde(tun3)
/ \
NULL pde(tun2)
Link: https://lkml.kernel.org/r/20251025024233.158363-1-albin_yang@163.com
Signed-off-by: Wei Yang <albinwyang(a)tencent.com>
Cc: Al Viro <viro(a)zeniv.linux.org.uk>
Cc: Christian Brauner <brauner(a)kernel.org>
Cc: wangzijie <wangzijie1(a)honor.com>
Cc: Alexey Dobriyan <adobriyan(a)gmail.com>
Cc: <stable(a)vger.kernel.org>
Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org>
---
fs/proc/generic.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)
--- a/fs/proc/generic.c~fs-proc-fix-uaf-in-proc_readdir_de
+++ a/fs/proc/generic.c
@@ -698,6 +698,12 @@ void pde_put(struct proc_dir_entry *pde)
}
}
+static void pde_erase(struct proc_dir_entry *pde, struct proc_dir_entry *parent)
+{
+ rb_erase(&pde->subdir_node, &parent->subdir);
+ RB_CLEAR_NODE(&pde->subdir_node);
+}
+
/*
* Remove a /proc entry and free it if it's not currently in use.
*/
@@ -720,7 +726,7 @@ void remove_proc_entry(const char *name,
WARN(1, "removing permanent /proc entry '%s'", de->name);
de = NULL;
} else {
- rb_erase(&de->subdir_node, &parent->subdir);
+ pde_erase(de, parent);
if (S_ISDIR(de->mode))
parent->nlink--;
}
@@ -764,7 +770,7 @@ int remove_proc_subtree(const char *name
root->parent->name, root->name);
return -EINVAL;
}
- rb_erase(&root->subdir_node, &parent->subdir);
+ pde_erase(root, parent);
de = root;
while (1) {
@@ -776,7 +782,7 @@ int remove_proc_subtree(const char *name
next->parent->name, next->name);
return -EINVAL;
}
- rb_erase(&next->subdir_node, &de->subdir);
+ pde_erase(next, de);
de = next;
continue;
}
_
Patches currently in -mm which might be from albinwyang(a)tencent.com are
fs-proc-fix-uaf-in-proc_readdir_de.patch
When btrfs_add_qgroup_relation() is called with invalid qgroup levels
(src >= dst), the function returns -EINVAL directly without freeing the
preallocated qgroup_list structure passed by the caller. This causes a
memory leak because the caller unconditionally sets the pointer to NULL
after the call, preventing any cleanup.
The issue occurs because the level validation check happens before the
mutex is acquired and before any error handling path that would free
the prealloc pointer. On this early return, the cleanup code at the
'out' label (which includes kfree(prealloc)) is never reached.
In btrfs_ioctl_qgroup_assign(), the code pattern is:
prealloc = kzalloc(sizeof(*prealloc), GFP_KERNEL);
ret = btrfs_add_qgroup_relation(trans, sa->src, sa->dst, prealloc);
prealloc = NULL; // Always set to NULL regardless of return value
...
kfree(prealloc); // This becomes kfree(NULL), does nothing
When the level check fails, 'prealloc' is never freed by either the
callee or the caller, resulting in a 64-byte memory leak per failed
operation. This can be triggered repeatedly by an unprivileged user
with access to a writable btrfs mount, potentially exhausting kernel
memory.
Fix this by freeing prealloc before the early return, ensuring prealloc
is always freed on all error paths.
Fixes: 8465ecec9611 ("btrfs: Check qgroup level in kernel qgroup assign.")
Cc: stable(a)vger.kernel.org # v4.0+
Signed-off-by: Shardul Bankar <shardulsb08(a)gmail.com>
---
v2:
- Free prealloc directly before returning -EINVAL (no mutex held),
per review from Qu Wenruo.
- Drop goto-based cleanup.
fs/btrfs/qgroup.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
index 1175b8192cd7..31ad8580322a 100644
--- a/fs/btrfs/qgroup.c
+++ b/fs/btrfs/qgroup.c
@@ -1539,8 +1539,10 @@ int btrfs_add_qgroup_relation(struct btrfs_trans_handle *trans, u64 src, u64 dst
ASSERT(prealloc);
/* Check the level of src and dst first */
- if (btrfs_qgroup_level(src) >= btrfs_qgroup_level(dst))
+ if (btrfs_qgroup_level(src) >= btrfs_qgroup_level(dst)) {
+ kfree(prealloc);
return -EINVAL;
+ }
mutex_lock(&fs_info->qgroup_ioctl_lock);
if (!fs_info->quota_root) {
--
2.34.1