Integer Overflow or Wraparound Affecting kernel-modules package, versions <0:5.14.0-503.19.1.el9_5
Threat Intelligence
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Start learning- Snyk IDSNYK-ALMALINUX9-KERNELMODULES-8621590
- published14 Jan 2025
- disclosed19 Dec 2024
Introduced: 19 Dec 2024
CVE-2024-49888 (opens in a new tab)How to fix?
Upgrade AlmaLinux:9 kernel-modules to version 0:5.14.0-503.19.1.el9_5 or higher.
This issue was patched in ALSA-2024:11486.
NVD Description
Note: Versions mentioned in the description apply only to the upstream kernel-modules package and not the kernel-modules package as distributed by AlmaLinux.
See How to fix? for AlmaLinux:9 relevant fixed versions and status.
In the Linux kernel, the following vulnerability has been resolved:
bpf: Fix a sdiv overflow issue
Zac Ecob reported a problem where a bpf program may cause kernel crash due to the following error: Oops: divide error: 0000 [#1] PREEMPT SMP KASAN PTI
The failure is due to the below signed divide: LLONG_MIN/-1 where LLONG_MIN equals to -9,223,372,036,854,775,808. LLONG_MIN/-1 is supposed to give a positive number 9,223,372,036,854,775,808, but it is impossible since for 64-bit system, the maximum positive number is 9,223,372,036,854,775,807. On x86_64, LLONG_MIN/-1 will cause a kernel exception. On arm64, the result for LLONG_MIN/-1 is LLONG_MIN.
Further investigation found all the following sdiv/smod cases may trigger an exception when bpf program is running on x86_64 platform:
- LLONG_MIN/-1 for 64bit operation
- INT_MIN/-1 for 32bit operation
- LLONG_MIN%-1 for 64bit operation
- INT_MIN%-1 for 32bit operation where -1 can be an immediate or in a register.
On arm64, there are no exceptions:
- LLONG_MIN/-1 = LLONG_MIN
- INT_MIN/-1 = INT_MIN
- LLONG_MIN%-1 = 0
- INT_MIN%-1 = 0 where -1 can be an immediate or in a register.
Insn patching is needed to handle the above cases and the patched codes produced results aligned with above arm64 result. The below are pseudo codes to handle sdiv/smod exceptions including both divisor -1 and divisor 0 and the divisor is stored in a register.
sdiv: tmp = rX tmp += 1 /* [-1, 0] -> [0, 1] if tmp >(unsigned) 1 goto L2 if tmp == 0 goto L1 rY = 0 L1: rY = -rY; goto L3 L2: rY /= rX L3:
smod: tmp = rX tmp += 1 /* [-1, 0] -> [0, 1] if tmp >(unsigned) 1 goto L1 if tmp == 1 (is64 ? goto L2 : goto L3) rY = 0; goto L2 L1: rY %= rX L2: goto L4 // only when !is64 L3: wY = wY // only when !is64 L4:
References
- https://errata.almalinux.org/9/ALSA-2024-11486.html
- https://access.redhat.com/security/cve/CVE-2024-49888
- https://access.redhat.com/errata/RHSA-2024:11486
- https://git.kernel.org/stable/c/4902a6a0dc593c82055fc8c9ada371bafe26c9cc
- https://git.kernel.org/stable/c/7dd34d7b7dcf9309fc6224caf4dd5b35bedddcb7
- https://git.kernel.org/stable/c/d22e45a369afc7c28f11acfa5b5e8e478227ca5d