CVE-2024-56558

nfsd: make sure exp active before svc_export_show

HIGH

7.8

CVSS Score

Published: December 27, 2024 at 02:23 PM UTC

Updated: August 5, 2026 at 12:05 PM UTC

1 product affected across 1 vendorLinux Kernel

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Severity

HIGH7.8

Exploit prediction

EPSS 0.2%

SSVC

No known exploit

Description

In the Linux kernel, the following vulnerability has been resolved: nfsd: make sure exp active before svc_export_show The function `e_show` was called with protection from RCU. This only ensures that `exp` will not be freed. Therefore, the reference count for `exp` can drop to zero, which will trigger a refcount use-after-free warning when `exp_get` is called. To resolve this issue, use `cache_get_rcu` to ensure that `exp` remains active. ------------[ cut here ]------------ refcount_t: addition on 0; use-after-free. WARNING: CPU: 3 PID: 819 at lib/refcount.c:25 refcount_warn_saturate+0xb1/0x120 CPU: 3 UID: 0 PID: 819 Comm: cat Not tainted 6.12.0-rc3+ #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.1-2.fc37 04/01/2014 RIP: 0010:refcount_warn_saturate+0xb1/0x120 ... Call Trace: <TASK> e_show+0x20b/0x230 [nfsd] seq_read_iter+0x589/0x770 seq_read+0x1e5/0x270 vfs_read+0x125/0x530 ksys_read+0xc1/0x160 do_syscall_64+0x5f/0x170 entry_SYSCALL_64_after_hwframe+0x76/0x7e

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Linux Kernel · Linux

95%

3.17 ≤ v < 5.10.2313.17 ≤ v < 5.15.1743.17 ≤ v < 5.4.2873.17 ≤ v < 6.1.1203.17 ≤ v < 6.12.43.17 ≤ v < 6.133.17 ≤ v < 6.6.645.11 ≤ v < 5.15.1745.16 ≤ v < 6.1.1205.5 ≤ v < 5.10.2316.2 ≤ v < 6.6.646.7 ≤ v < 6.12.43.17bf18f163e89c52e09c96534db45c4274273a0b34

Vendor states this is fixed in 1cecfdbc6bfc89c516d286884c7f29267b95de2b (fixed)

Vendor states this is fixed in 6cefcadd34e3c71c81ea64b899a0daa86314a51a (fixed)

Vendor states this is fixed in 7365d1f8de63cffdbbaa2287ce0205438e1a922f (fixed)

Vendor states this is fixed in 7d8f7816bebcd2e7400bb4d786eccb8f33c9f9ec (fixed)

Vendor states this is fixed in 7fd29d284b55c2274f7a748e6c5f25b4758b8da5 (fixed)

Vendor states this is fixed in be8f982c369c965faffa198b46060f8853e0f1f0 (fixed)

Vendor states this is fixed in e2fa0d0e327279a8defb87b263cd0bf288fd9261 (fixed)

Vendor states this is fixed in 3.17 (unaffected)

Vendor states this is fixed in 5.10.231 (unaffected)

Vendor states this is fixed in 5.15.174 (unaffected)

Vendor states this is fixed in 5.4.287 (unaffected)

Vendor states this is fixed in 6.1.120 (unaffected)