skmsg: Skip zero length skb in sk_msg_recvmsg
When running BPF selftests (./test_progs -t sockmap_basic) on a Loongarch
platform, the following kernel panic occurs:
[...]
Oops[#1]:
CPU: 22 PID: 2824 Comm: test_progs Tainted: G OE 6.10.0-rc2+ #18
Hardware name: LOONGSON Dabieshan/Loongson-TC542F0, BIOS Loongson-UDK2018
... ...
ra: 90000000048bf6c0 sk_msg_recvmsg+0x120/0x560
ERA: 9000000004162774 copy_page_to_iter+0x74/0x1c0
CRMD: 000000b0 (PLV0 -IE -DA +PG DACF=CC DACM=CC -WE)
PRMD: 0000000c (PPLV0 +PIE +PWE)
EUEN: 00000007 (+FPE +SXE +ASXE -BTE)
ECFG: 00071c1d (LIE=0,2-4,10-12 VS=7)
ESTAT: 00010000 [PIL] (IS= ECode=1 EsubCode=0)
BADV: 0000000000000040
PRID: 0014c011 (Loongson-64bit, Loongson-3C5000)
Modules linked in: bpf_testmod(OE) xt_CHECKSUM xt_MASQUERADE xt_conntrack
Process test_progs (pid: 2824, threadinfo=0000000000863a31, task=...)
Stack : ...
Call Trace:
[<9000000004162774>] copy_page_to_iter+0x74/0x1c0
[<90000000048bf6c0>] sk_msg_recvmsg+0x120/0x560
[<90000000049f2b90>] tcp_bpf_recvmsg_parser+0x170/0x4e0
[<90000000049aae34>] inet_recvmsg+0x54/0x100
[<900000000481ad5c>] sock_recvmsg+0x7c/0xe0
[<900000000481e1a8>] __sys_recvfrom+0x108/0x1c0
[<900000000481e27c>] sys_recvfrom+0x1c/0x40
[<9000000004c076ec>] do_syscall+0x8c/0xc0
[<9000000003731da4>] handle_syscall+0xc4/0x160
Code: ...
---[ end trace 0000000000000000 ]---
Kernel panic - not syncing: Fatal exception
Kernel relocated by 0x3510000
.text @ 0x9000000003710000
.data @ 0x9000000004d70000
.bss @ 0x9000000006469400
---[ end Kernel panic - not syncing: Fatal exception ]---
[...]
This crash happens every time when running sockmap_skb_verdict_shutdown
subtest in sockmap_basic.
This crash is because a NULL pointer is passed to page_address() in the
sk_msg_recvmsg(). Due to the different implementations depending on the
architecture, page_address(NULL) will trigger a panic on Loongarch
platform but not on x86 platform. So this bug was hidden on x86 platform
for a while, but now it is exposed on Loongarch platform. The root cause
is that a zero length skb (skb->len == 0) was put on the queue.
This zero length skb is a TCP FIN packet, which was sent by shutdown(),
invoked in test_sockmap_skb_verdict_shutdown():
shutdown(p1, SHUT_WR);
In this case, in sk_psock_skb_ingress_enqueue(), num_sge is zero, and no
page is put to this sge (see sg_set_page in sg_set_page), but this empty
sge is queued into ingress_msg list.
And in sk_msg_recvmsg(), this empty sge is used, and a NULL page is got by
sg_page(sge). Pass this NULL page to copy_page_to_iter(), which passes it
to kmap_local_page() and to page_address(), then kernel panics.
To solve this, we should skip this zero length skb. So in sk_msg_recvmsg(),
if copy is zero, that means it's a zero length skb, skip invoking
copy_page_to_iter(). We are using the EFAULT return triggered by
copy_page_to_iter to check for is_fin in tcp_bpf.c.
Metrics
Affected Vendors & Products
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
Mon, 05 May 2025 21:15:00 +0000
Type | Values Removed | Values Added |
---|---|---|
Metrics |
ssvc
|
Thu, 13 Feb 2025 00:45:00 +0000
Type | Values Removed | Values Added |
---|---|---|
Metrics |
threat_severity
|
threat_severity
|
Mon, 03 Feb 2025 16:00:00 +0000
Type | Values Removed | Values Added |
---|---|---|
First Time appeared |
Linux
Linux linux Kernel |
|
CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.10:rc1:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.10:rc2:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.10:rc3:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.10:rc4:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.10:rc5:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.10:rc6:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:6.10:rc7:*:*:*:*:*:* |
|
Vendors & Products |
Linux
Linux linux Kernel |
|
Metrics |
cvssV3_1
|
cvssV3_1
|
Wed, 11 Sep 2024 18:30:00 +0000
Type | Values Removed | Values Added |
---|---|---|
Metrics |
ssvc
|
Wed, 11 Sep 2024 13:30:00 +0000
Type | Values Removed | Values Added |
---|---|---|
Metrics |
ssvc
|
Fri, 06 Sep 2024 13:45:00 +0000
Type | Values Removed | Values Added |
---|---|---|
Weaknesses | CWE-476 | |
Metrics |
cvssV3_1
|
cvssV3_1
|

Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2025-05-04T09:20:54.907Z
Reserved: 2024-07-12T12:17:45.625Z
Link: CVE-2024-41048

Updated: 2024-08-02T04:46:51.622Z

Status : Analyzed
Published: 2024-07-29T15:15:13.103
Modified: 2025-02-03T15:44:16.613
Link: CVE-2024-41048


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