CVE-2026-72431alloc_tag: fix use-after-free in /proc/allocinfo after module unload

Official 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.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/37e3e8a2c3bfdd503209f043f8bbfbdcf5a1d92f
• https://git.kernel.org/stable/c/008ceffd44040f809aead6d7bef7cb1210c4149a
• https://git.kernel.org/stable/c/2956268efc457cb05d29c1bf94de1e8e684d7bbc