alloc_tag: fix use-after-free in /proc/allocinfo after module unload
allocinfo_start() only reinitializes the codetag iterator at position 0.
For subsequent reads (position > 0), it reuses cached iterator state from
the previous batch. allocinfo_stop() drops mod_lock between read batches,
which allows module unload to complete and free the module memory that the
cached iterator still references:
CPU0 (read) CPU1 (rmmod)
---- ----
allocinfo_start(pos=0)
down_read(mod_lock)
allocinfo_show()
...
allocinfo_stop()
up_read(mod_lock)
codetag_unload_module()
kfree(cmod)
release_module_tags()
...
free_mod_mem()
allocinfo_start(pos=N)
down_read(mod_lock)
// reuses cached iter, skips re-init
allocinfo_show()
ct->filename <-- UAF
After free_mod_mem() frees the module's .rodata, allocinfo_show()
dereferences ct->filename, ct->function which point there.
Save the iterator state in allocinfo_next() and resume from it in
allocinfo_start() with codetag_next_ct(), which detects module removal via
idr_find() returning NULL and skips to the next module.
Analysis
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Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux | unaffected |
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| Linux | Linux | affected |
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No data available yet.
No vendor fix or workaround currently provided.
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Sat, 15 Aug 2026 06:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: alloc_tag: fix use-after-free in /proc/allocinfo after module unload allocinfo_start() only reinitializes the codetag iterator at position 0. For subsequent reads (position > 0), it reuses cached iterator state from the previous batch. allocinfo_stop() drops mod_lock between read batches, which allows module unload to complete and free the module memory that the cached iterator still references: CPU0 (read) CPU1 (rmmod) ---- ---- allocinfo_start(pos=0) down_read(mod_lock) allocinfo_show() ... allocinfo_stop() up_read(mod_lock) codetag_unload_module() kfree(cmod) release_module_tags() ... free_mod_mem() allocinfo_start(pos=N) down_read(mod_lock) // reuses cached iter, skips re-init allocinfo_show() ct->filename <-- UAF After free_mod_mem() frees the module's .rodata, allocinfo_show() dereferences ct->filename, ct->function which point there. Save the iterator state in allocinfo_next() and resume from it in allocinfo_start() with codetag_next_ct(), which detects module removal via idr_find() returning NULL and skips to the next module. | |
| Title | alloc_tag: fix use-after-free in /proc/allocinfo after module unload | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-08-15T05:56:46.821Z
Reserved: 2026-08-09T03:40:39.929Z
Link: CVE-2026-72431
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-08-15T06:22:16.960
Modified: 2026-08-15T06:22:16.960
Link: CVE-2026-72431
Redhat
No data.
OpenCVE Enrichment
No data.
No weakness.