In the Linux kernel, the following vulnerability has been resolved:
bpf: Explicitly check accesses to bpf_sock_addr
Syzkaller found a kernel warning on the following sock_addr program:
0: r0 = 0
1: r2 = *(u32 *)(r1 +60)
2: exit
which triggers:
verifier bug: error during ctx access conversion (0)
This is happening because offset 60 in bpf_sock_addr corresponds to an
implicit padding of 4 bytes, right after msg_src_ip4. Access to this
padding isn't rejected in sock_addr_is_valid_access and it thus later
fails to convert the access.
This patch fixes it by explicitly checking the various fields of
bpf_sock_addr in sock_addr_is_valid_access.
I checked the other ctx structures and is_valid_access functions and
didn't find any other similar cases. Other cases of (properly handled)
padding are covered in new tests in a subsequent patch.
bpf: Explicitly check accesses to bpf_sock_addr
Syzkaller found a kernel warning on the following sock_addr program:
0: r0 = 0
1: r2 = *(u32 *)(r1 +60)
2: exit
which triggers:
verifier bug: error during ctx access conversion (0)
This is happening because offset 60 in bpf_sock_addr corresponds to an
implicit padding of 4 bytes, right after msg_src_ip4. Access to this
padding isn't rejected in sock_addr_is_valid_access and it thus later
fails to convert the access.
This patch fixes it by explicitly checking the various fields of
bpf_sock_addr in sock_addr_is_valid_access.
I checked the other ctx structures and is_valid_access functions and
didn't find any other similar cases. Other cases of (properly handled)
padding are covered in new tests in a subsequent patch.
Metrics
Affected Vendors & Products
No data.
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Advisories
No advisories yet.
Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Tue, 28 Oct 2025 12:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: bpf: Explicitly check accesses to bpf_sock_addr Syzkaller found a kernel warning on the following sock_addr program: 0: r0 = 0 1: r2 = *(u32 *)(r1 +60) 2: exit which triggers: verifier bug: error during ctx access conversion (0) This is happening because offset 60 in bpf_sock_addr corresponds to an implicit padding of 4 bytes, right after msg_src_ip4. Access to this padding isn't rejected in sock_addr_is_valid_access and it thus later fails to convert the access. This patch fixes it by explicitly checking the various fields of bpf_sock_addr in sock_addr_is_valid_access. I checked the other ctx structures and is_valid_access functions and didn't find any other similar cases. Other cases of (properly handled) padding are covered in new tests in a subsequent patch. | |
| Title | bpf: Explicitly check accesses to bpf_sock_addr | |
| References |
|
|
MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2025-10-28T11:48:43.548Z
Reserved: 2025-04-16T07:20:57.160Z
Link: CVE-2025-40078
Vulnrichment
No data.
NVD
Status : Received
Published: 2025-10-28T12:15:42.360
Modified: 2025-10-28T12:15:42.360
Link: CVE-2025-40078
Redhat
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OpenCVE Enrichment
No data.