apparmor: fix integer overflow in verify_tags() bounds check
Summary
| CVE | CVE-2026-90246 |
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| State | PUBLISHED |
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| Assigner | Linux |
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| Source Priority | CVE Program / NVD first with legacy fallback |
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| Published | 2026-09-17 17:17:20 UTC |
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| Updated | 2026-09-17 17:17:20 UTC |
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| Description | In the Linux kernel, the following vulnerability has been resolved:
apparmor: fix integer overflow in verify_tags() bounds check
verify_tags() validates the tagset table unpacked from a policy blob.
For each set it reads a count and checks that advancing the index by
that count stays inside sets.table[]:
u32 cnt = tags->sets.table[i];
if (i+cnt >= tags->sets.size) {
i, cnt and sets.size are all u32, so i+cnt is evaluated modulo 2^32.
sets.table[] is filled by unpack_tagsets() with aa_unpack_u32(), so
every entry is a raw unbounded 32-bit word taken from the policy blob,
and verify_tags() is the function that is supposed to validate it. A
count close to U32_MAX makes the sum wrap to a small value, the guard
passes, and the inner loop then walks sets.table[++i] past the end of
the kcalloc(size, sizeof(u32)) allocation.
Note that sets.size is bounded by 65535, because unpack_tagsets() reads
it with aa_unpack_array() as a u16, so the wrap cannot be reached by
growing the table; it is reached purely through the attacker-supplied
count.
With sets.size = 2 and sets.table = { 0, 0xffffffff }:
i = 0: cnt = 0, guard 0 + 0 >= 2 is false, inner loop does not run
i = 1: cnt = 0xffffffff, guard (1 + 0xffffffff) mod 2^32 == 0 >= 2 is
false, so the guard is bypassed and the inner loop reads
sets.table[2] -- one element past a two element allocation
The walk continues until an out-of-bounds value happens to be >=
hdrs.size or the access faults, so a crafted policy yields an
out-of-bounds read on the policy load path
(aa_replace_profiles -> aa_unpack -> unpack_policydb -> unpack_tags ->
verify_tags). unpack_tags() runs before the perms and DFA tables are
unpacked, so no other table needs to be well formed to reach it.
Policy load is gated by aa_may_manage_policy(), which checks
CAP_MAC_ADMIN relative to the subject's own user namespace rather than
the init user namespace, so with the default
unprivileged_userns_apparmor_policy=1 the path is reachable from an
unprivileged task in a matched-level nested namespace, not only by a
globally privileged one.
Perform the addition in u64 so that it cannot wrap, restoring the
intended i + cnt < sets.size guarantee. |
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Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
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| CNA |
Linux |
Linux |
affected 3d28e2397af7a89ac3de33c686ed404cda59b5d5 ef79a405f83993f0fda5efde371d98433f7d7a47 git |
Not specified |
| CNA |
Linux |
Linux |
affected 3d28e2397af7a89ac3de33c686ed404cda59b5d5 465946d3c560c0137e6a180ba054dddc4d049f5a git |
Not specified |
| CNA |
Linux |
Linux |
affected 7.0 |
Not specified |
| CNA |
Linux |
Linux |
unaffected 7.0 semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 7.2.6 7.2.* semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 7.3-rc1 * original_commit_for_fix |
Not specified |
References
| Reference | Source | Link | Tags |
|---|
| git.kernel.org/stable/c/ef79a405f83993f0fda5efde371d98433f7d7a47 |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/465946d3c560c0137e6a180ba054dddc4d049f5a |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| CVE Program record |
CVE.ORG |
www.cve.org |
canonical |
| NVD vulnerability detail |
NVD |
nvd.nist.gov |
canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.