cbcvebase.
CVE-2024-47702
published 2024-10-21

CVE-2024-47702: In the Linux kernel, the following vulnerability has been resolved: bpf: Fail verification for sign-extension of packet data/data_end/data_meta syzbot reported…

PriorityP421medium5.5CVSS 3.1
AVLACLPRLUINSUCNINAH
EPSS
0.20%
10.5th percentile
In the Linux kernel, the following vulnerability has been resolved: bpf: Fail verification for sign-extension of packet data/data_end/data_meta syzbot reported a kernel crash due to commit 1f1e864b6555 ("bpf: Handle sign-extenstin ctx member accesses"). The reason is due to sign-extension of 32-bit load for packet data/data_end/data_meta uapi field. The original code looks like: r2 = *(s32 *)(r1 + 76) /* load __sk_buff->data */ r3 = *(u32 *)(r1 + 80) /* load __sk_buff->data_end */ r0 = r2 r0 += 8 if r3 > r0 goto +1 ... Note that __sk_buff->data load has 32-bit sign extension. After verification and convert_ctx_accesses(), the final asm code looks like: r2 = *(u64 *)(r1 +208) r2 = (s32)r2 r3 = *(u64 *)(r1 +80) r0 = r2 r0 += 8 if r3 > r0 goto pc+1 ... Note that 'r2 = (s32)r2' may make the kernel __sk_buff->data address invalid which may cause runtime failure. Currently, in C code, typically we have void *data = (void *)(long)skb->data; void *data_end = (void *)(long)skb->data_end; ... and it will generate r2 = *(u64 *)(r1 +208) r3 = *(u64 *)(r1 +80) r0 = r2 r0 += 8 if r3 > r0 goto pc+1 If we allow sign-extension, void *data = (void *)(long)(int)skb->data; void *data_end = (void *)(long)skb->data_end; ... the generated code looks like r2 = *(u64 *)(r1 +208) r2 >= 32 r3 = *(u64 *)(r1 +80) r0 = r2 r0 += 8 if r3 > r0 goto pc+1 and this will cause verification failure since "r2 data */ this patch added additional checking in is_valid_access() callback function for packet data/data_end/data_meta access. If those accesses are with sign-extenstion, the verification will fail. [1] https://lore.kernel.org/bpf/[email protected]/

Affected

21 ranges
VendorProductVersion rangeFixed in
debianlinux< linux 6.11.2-1 (forky)linux 6.11.2-1 (forky)
linuxlinux
linuxlinux>= 1f1e864b65554e33fe74e3377e58b12f4302f2eb < f1620c93a1ec950d87ef327a565d3907736d3340f1620c93a1ec950d87ef327a565d3907736d3340
linuxlinux>= 1f1e864b65554e33fe74e3377e58b12f4302f2eb < f09757fe97a225ae505886eac572e4cbfba96537f09757fe97a225ae505886eac572e4cbfba96537
linuxlinux>= 1f1e864b65554e33fe74e3377e58b12f4302f2eb < 92de36080c93296ef9005690705cba260b9bd68a92de36080c93296ef9005690705cba260b9bd68a
linuxlinux_kernel>= 0 < 6.11.2-16.11.2-1
linuxlinux_kernel>= 0 < 6.11.2-16.11.2-1
linuxlinux_kernel>= 0 < 6.8.0-54.566.8.0-54.56
linuxlinux_kernel>= 0 < 6.11.0-18.186.11.0-18.18
linuxlinux_kernel>= 6.11 < 6.11.26.11.2
linuxlinux_kernel>= 6.6 < 6.10.136.10.13
msrcazl3_kernel_6.6.104.2-4_on_azure_linux_3.0
msrcazl3_kernel_6.6.112.1-2_on_azure_linux_3.0
msrcazl3_kernel_6.6.117.1-1_on_azure_linux_3.0
msrcazl3_kernel_6.6.119.3-1_on_azure_linux_3.0
msrcazl3_kernel_6.6.119.3-3_on_azure_linux_3.0
msrcazl3_kernel_6.6.121.1-1_on_azure_linux_3.0
msrcazl3_kernel_6.6.126.1-1_on_azure_linux_3.0
msrcazl3_kernel_6.6.130.1-3_on_azure_linux_3.0
msrcazl3_kernel_6.6.96.2-1_on_azure_linux_3.0
msrcazl3_kernel_6.6.96.2-2_on_azure_linux_3.0

CVSS provenance

nvdv3.15.5MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
osv8.8HIGH
vendor_ubuntu8.8HIGH
vendor_debian5.5LOW
vendor_msrc5.5MEDIUM
vendor_redhat5.5MEDIUM
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