cbcvebase.
CVE-2022-49961
published 2025-06-18

CVE-2022-49961: In the Linux kernel, the following vulnerability has been resolved: bpf: Do mark_chain_precision for ARG_CONST_ALLOC_SIZE_OR_ZERO Precision markers need to be…

PriorityP431high7.1CVSS 3.1
AVLACLPRLUINSUCHINAH
EPSS
0.22%
12.9th percentile
In the Linux kernel, the following vulnerability has been resolved: bpf: Do mark_chain_precision for ARG_CONST_ALLOC_SIZE_OR_ZERO Precision markers need to be propagated whenever we have an ARG_CONST_* style argument, as the verifier cannot consider imprecise scalars to be equivalent for the purposes of states_equal check when such arguments refine the return value (in this case, set mem_size for PTR_TO_MEM). The resultant mem_size for the R0 is derived from the constant value, and if the verifier incorrectly prunes states considering them equivalent where such arguments exist (by seeing that both registers have reg->precise as false in regsafe), we can end up with invalid programs passing the verifier which can do access beyond what should have been the correct mem_size in that explored state. To show a concrete example of the problem: 0000000000000000 : 0: r2 = *(u32 *)(r1 + 80) 1: r1 = *(u32 *)(r1 + 76) 2: r3 = r1 3: r3 += 4 4: if r3 > r2 goto +18 5: w2 = 0 6: *(u32 *)(r1 + 0) = r2 7: r1 = *(u32 *)(r1 + 0) 8: r2 = 1 9: if w1 == 0 goto +1 10: r2 = -1 0000000000000058 : 11: r1 = 0 ll 13: r3 = 0 14: call bpf_ringbuf_reserve 15: if r0 == 0 goto +7 16: r1 = r0 17: r1 += 16777215 18: w2 = 0 19: *(u8 *)(r1 + 0) = r2 20: r1 = r0 21: r2 = 0 22: call bpf_ringbuf_submit 00000000000000b8 : 23: w0 = 0 24: exit For the first case, the single line execution's exploration will prune the search at insn 14 for the branch insn 9's second leg as it will be verified first using r2 = -1 (UINT_MAX), while as w1 at insn 9 will always be 0 so at runtime we don't get error for being greater than UINT_MAX/4 from bpf_ringbuf_reserve. The verifier during regsafe just sees reg->precise as false for both r2 registers in both states, hence considers them equal for purposes of states_equal. If we propagated precise markers using the backtracking support, we would use the precise marking to then ensure that old r2 (UINT_MAX) was within the new r2 (1) and this would never be true, so the v

Affected

38 ranges· showing 25
VendorProductVersion rangeFixed in
debianlinux< linux 5.19.11-1 (bookworm)linux 5.19.11-1 (bookworm)
linuxlinux
linuxlinux>= 457f44363a8894135c85b7a9afd2bd8196db24ab < 987b4c465ba28c662ca857be6c20fd2d96bc55f0987b4c465ba28c662ca857be6c20fd2d96bc55f0
linuxlinux>= 457f44363a8894135c85b7a9afd2bd8196db24ab < 2459615a8d7f44ac81f0965bc094e55ccb2547172459615a8d7f44ac81f0965bc094e55ccb254717
linuxlinux>= 457f44363a8894135c85b7a9afd2bd8196db24ab < 2fc31465c5373b5ca4edf2e5238558cb629023112fc31465c5373b5ca4edf2e5238558cb62902311
linuxlinux_kernel
linuxlinux_kernel>= 0 < 5.19.11-15.19.11-1
linuxlinux_kernel>= 0 < 5.19.11-15.19.11-1
linuxlinux_kernel>= 0 < 5.19.11-15.19.11-1
linuxlinux_kernel>= 5.8 < 5.19.85.19.8
msrccbl2_kernel_5.15.186.1-1_on_cbl_mariner_2.0
msrccbl2_kernel_5.15.200.1-1_on_cbl_mariner_2.0
msrccbl2_kernel_5.15.202.1-1_on_cbl_mariner_2.0
ubuntulinux
ubuntulinux-aws
ubuntulinux-aws-5.15
ubuntulinux-aws-fips
ubuntulinux-azure-5.15
ubuntulinux-azure-fde
ubuntulinux-azure-fde-5.15
ubuntulinux-fips
ubuntulinux-gcp
ubuntulinux-gcp-fips
ubuntulinux-gke
ubuntulinux-gkeop

CVSS provenance

nvdv3.17.1HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
osv7.1HIGH
vendor_debian7.1HIGH
vendor_redhat7.1HIGH
vendor_ubuntu7.1HIGH
vendor_msrc6.0MEDIUM
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