bpf: Fix overloading of MEM_UNINIT's meaning

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2024-50164
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2024-11-07 10:15:07 UTC
Updated2026-07-14 13:17:11 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: bpf: Fix overloading of MEM_UNINIT's meaning Lonial reported an issue in the BPF verifier where check_mem_size_reg() has the following code: if (!tnum_is_const(reg->var_off)) /* For unprivileged variable accesses, disable raw * mode so that the program is required to * initialize all the memory that the helper could * just partially fill up. */ meta = NULL; This means that writes are not checked when the register containing the size of the passed buffer has not a fixed size. Through this bug, a BPF program can write to a map which is marked as read-only, for example, .rodata global maps. The problem is that MEM_UNINIT's initial meaning that "the passed buffer to the BPF helper does not need to be initialized" which was added back in commit 435faee1aae9 ("bpf, verifier: add ARG_PTR_TO_RAW_STACK type") got overloaded over time with "the passed buffer is being written to". The problem however is that checks such as the above which were added later via 06c1c049721a ("bpf: allow helpers access to variable memory") set meta to NULL in order force the user to always initialize the passed buffer to the helper. Due to the current double meaning of MEM_UNINIT, this bypasses verifier write checks to the memory (not boundary checks though) and only assumes the latter memory is read instead. Fix this by reverting MEM_UNINIT back to its original meaning, and having MEM_WRITE as an annotation to BPF helpers in order to then trigger the BPF verifier checks for writing to memory. Some notes: check_arg_pair_ok() ensures that for ARG_CONST_SIZE{,_OR_ZERO} we can access fn->arg_type[arg - 1] since it must contain a preceding ARG_PTR_TO_MEM. For check_mem_reg() the meta argument can be removed altogether since we do check both BPF_READ and BPF_WRITE. Same for the equivalent check_kfunc_mem_size_reg().

Risk And Classification

Primary CVSS: v3.1 7.1 HIGH from [email protected]

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H

Problem Types: NVD-CWE-noinfo

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Linux Linux Kernel All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 97e6d7dab1ca4648821c790a2b7913d6d5d549db 43f4df339a4d375bedcad29a61ae6f0ee7a048f8 git Not specified
CNA Linux Linux affected 97e6d7dab1ca4648821c790a2b7913d6d5d549db 48068ccaea957469f1adf78dfd2c1c9a7e18f0fe git Not specified
CNA Linux Linux affected 97e6d7dab1ca4648821c790a2b7913d6d5d549db 54bc31682660810af1bed7ca7a19f182df8d3df8 git Not specified
CNA Linux Linux affected 97e6d7dab1ca4648821c790a2b7913d6d5d549db 8ea607330a39184f51737c6ae706db7fdca7628e git Not specified
CNA Linux Linux affected 6099a6c8a749a5c8d5f8b4c4342022a92072a02b git Not specified
CNA Linux Linux affected bfe25df63048edd4ceaf78a2fc755d5e2befc978 git Not specified
CNA Linux Linux affected 717c39718dbc4f7ebcbb7b625fb11851cd9007fe git Not specified
CNA Linux Linux affected 5d0bba8232bf22ce13747cbfc8f696318ff01a50 git Not specified
CNA Linux Linux affected 70674d11d14eeecad90be4b409a22b902112ba32 git Not specified
CNA Linux Linux affected a08d942ecbf46e23a192093f6983cb1d779f4fa8 git Not specified
CNA Linux Linux affected 5.15.45 5.16 semver Not specified
CNA Linux Linux affected 5.17.13 5.18 semver Not specified
CNA Linux Linux affected 5.18.2 5.19 semver Not specified
CNA Linux Linux affected 5.19 Not specified
CNA Linux Linux unaffected 5.19 semver Not specified
CNA Linux Linux unaffected 6.1.125 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.59 6.6.* semver Not specified
CNA Linux Linux unaffected 6.11.6 6.11.* semver Not specified
CNA Linux Linux unaffected 6.12 * original_commit_for_fix Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.6 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.6 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP affected V3.1.6 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP affected V3.1.6 * custom Not specified
ADP Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.6 * custom Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/8ea607330a39184f51737c6ae706db7fdca7628e 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/48068ccaea957469f1adf78dfd2c1c9a7e18f0fe 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/54bc31682660810af1bed7ca7a19f182df8d3df8 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
cert-portal.siemens.com/productcert/html/ssa-019113.html 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e cert-portal.siemens.com
lists.debian.org/debian-lts-announce/2025/03/msg00001.html af854a3a-2127-422b-91ae-364da2661108 lists.debian.org
git.kernel.org/stable/c/43f4df339a4d375bedcad29a61ae6f0ee7a048f8 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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