In the Linux kernel, the following vulnerability has been resolved:
tcp: fix page frag corruption on page fault
Steffen reported a TCP stream corruption for HTTP requests
served by the apache web-server using a cifs mount-point
and memory mapping the relevant file.
The root cause is quite similar to the one addressed by
commit 20eb4f29b602 ("net: fix sk_page_frag() recursion from
memory reclaim"). Here the nested access to the task page frag
is caused by a page fault on the (mmapped) user-space memory
buffer coming from the cifs file.
The page fault handler performs an smb transaction on a different
socket, inside the same process context. Since sk->sk_allaction
for such socket does not prevent the usage for the task_frag,
the nested allocation modify "under the hood" the page frag
in use by the outer sendmsg call, corrupting the stream.
The overall relevant stack trace looks like the following:
httpd 78268 [001] 3461630.850950:      probe:tcp_sendmsg_locked:
        ffffffff91461d91 tcp_sendmsg_locked+0x1
        ffffffff91462b57 tcp_sendmsg+0x27
        ffffffff9139814e sock_sendmsg+0x3e
        ffffffffc06dfe1d smb_send_kvec+0x28
        [...]
        ffffffffc06cfaf8 cifs_readpages+0x213
        ffffffff90e83c4b read_pages+0x6b
        ffffffff90e83f31 __do_page_cache_readahead+0x1c1
        ffffffff90e79e98 filemap_fault+0x788
        ffffffff90eb0458 __do_fault+0x38
        ffffffff90eb5280 do_fault+0x1a0
        ffffffff90eb7c84 __handle_mm_fault+0x4d4
        ffffffff90eb8093 handle_mm_fault+0xc3
        ffffffff90c74f6d __do_page_fault+0x1ed
        ffffffff90c75277 do_page_fault+0x37
        ffffffff9160111e page_fault+0x1e
        ffffffff9109e7b5 copyin+0x25
        ffffffff9109eb40 _copy_from_iter_full+0xe0
        ffffffff91462370 tcp_sendmsg_locked+0x5e0
        ffffffff91462370 tcp_sendmsg_locked+0x5e0
        ffffffff91462b57 tcp_sendmsg+0x27
        ffffffff9139815c sock_sendmsg+0x4c
        ffffffff913981f7 sock_write_iter+0x97
        ffffffff90f2cc56 do_iter_readv_writev+0x156
        ffffffff90f2dff0 do_iter_write+0x80
        ffffffff90f2e1c3 vfs_writev+0xa3
        ffffffff90f2e27c do_writev+0x5c
        ffffffff90c042bb do_syscall_64+0x5b
        ffffffff916000ad entry_SYSCALL_64_after_hwframe+0x65
The cifs filesystem rightfully sets sk_allocations to GFP_NOFS,
we can avoid the nesting using the sk page frag for allocation
lacking the __GFP_FS flag. Do not define an additional mm-helper
for that, as this is strictly tied to the sk page frag usage.
v1 -> v2:
 - use a stricted sk_page_frag() check instead of reordering the
   code (Eric)
                
            Metrics
Affected Vendors & Products
References
        History
                    Thu, 18 Sep 2025 16:15:00 +0000
| Type | Values Removed | Values Added | 
|---|---|---|
| First Time appeared | Linux Linux linux Kernel | |
| Weaknesses | NVD-CWE-noinfo | |
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:5.16:rc1:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:5.16:rc2:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:5.16:rc3:*:*:*:*:*:* | |
| Vendors & Products | Linux Linux linux Kernel | |
| Metrics | cvssV3_1 
 | cvssV3_1 
 | 
Mon, 04 Nov 2024 12:15:00 +0000
| Type | Values Removed | Values Added | 
|---|---|---|
| Metrics | ssvc 
 | 
Tue, 08 Oct 2024 02:30:00 +0000
| Type | Values Removed | Values Added | 
|---|---|---|
| First Time appeared | Redhat Redhat enterprise Linux Redhat rhel Aus Redhat rhel E4s Redhat rhel Eus Redhat rhel Tus | |
| CPEs | cpe:/a:redhat:enterprise_linux:8::nfv cpe:/o:redhat:enterprise_linux:8 cpe:/o:redhat:rhel_aus:8.2 cpe:/o:redhat:rhel_e4s:8.2 cpe:/o:redhat:rhel_eus:8.4 cpe:/o:redhat:rhel_tus:8.2 | |
| Vendors & Products | Redhat Redhat enterprise Linux Redhat rhel Aus Redhat rhel E4s Redhat rhel Eus Redhat rhel Tus | 
 MITRE
                        MITRE
                    Status: PUBLISHED
Assigner: Linux
Published: 2024-05-24T15:09:49.895Z
Updated: 2025-05-04T07:13:12.226Z
Reserved: 2024-05-24T15:02:54.829Z
Link: CVE-2021-47544
 Vulnrichment
                        Vulnrichment
                    Updated: 2024-08-04T05:39:59.619Z
 NVD
                        NVD
                    Status : Analyzed
Published: 2024-05-24T15:15:18.983
Modified: 2025-09-18T16:08:22.567
Link: CVE-2021-47544
 Redhat
                        Redhat