CVE-2025-21999

Description

In the Linux kernel, the following vulnerability has been resolved: proc: fix UAF in proc_get_inode() Fix race between rmmod and /proc/XXX's inode instantiation. The bug is that pde->proc_ops don't belong to /proc, it belongs to a module, therefore dereferencing it after /proc entry has been registered is a bug unless use_pde/unuse_pde() pair has been used. use_pde/unuse_pde can be avoided (2 atomic ops!) because pde->proc_ops never changes so information necessary for inode instantiation can be saved _before_ proc_register() in PDE itself and used later, avoiding pde->proc_ops->... dereference. rmmod lookup sys_delete_module proc_lookup_de pde_get(de); proc_get_inode(dir->i_sb, de); mod->exit() proc_remove remove_proc_subtree proc_entry_rundown(de); free_module(mod); if (S_ISREG(inode->i_mode)) if (de->proc_ops->proc_read_iter) --> As module is already freed, will trigger UAF BUG: unable to handle page fault for address: fffffbfff80a702b PGD 817fc4067 P4D 817fc4067 PUD 817fc0067 PMD 102ef4067 PTE 0 Oops: Oops: 0000 [#1] PREEMPT SMP KASAN PTI CPU: 26 UID: 0 PID: 2667 Comm: ls Tainted: G Hardware name: QEMU Standard PC (i440FX + PIIX, 1996) RIP: 0010:proc_get_inode+0x302/0x6e0 RSP: 0018:ffff88811c837998 EFLAGS: 00010a06 RAX: dffffc0000000000 RBX: ffffffffc0538140 RCX: 0000000000000007 RDX: 1ffffffff80a702b RSI: 0000000000000001 RDI: ffffffffc0538158 RBP: ffff8881299a6000 R08: 0000000067bbe1e5 R09: 1ffff11023906f20 R10: ffffffffb560ca07 R11: ffffffffb2b43a58 R12: ffff888105bb78f0 R13: ffff888100518048 R14: ffff8881299a6004 R15: 0000000000000001 FS: 00007f95b9686840(0000) GS:ffff8883af100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: fffffbfff80a702b CR3: 0000000117dd2000 CR4: 00000000000006f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> proc_lookup_de+0x11f/0x2e0 __lookup_slow+0x188/0x350 walk_component+0x2ab/0x4f0 path_lookupat+0x120/0x660 filename_lookup+0x1ce/0x560 vfs_statx+0xac/0x150 __do_sys_newstat+0x96/0x110 do_syscall_64+0x5f/0x170 entry_SYSCALL_64_after_hwframe+0x76/0x7e [adobriyan@gmail.com: don't do 2 atomic ops on the common path]

Reserved 2024-12-29 | Published 2025-04-03 | Updated 2025-05-04 | Assigner Linux

Product status

Default status
unaffected

778f3dd5a13c9e1642e0b2efea4b769387a70afa before eda279586e571b05dff44d48e05f8977ad05855d
affected

778f3dd5a13c9e1642e0b2efea4b769387a70afa before 4b0b8445b6fd41e6f62ac90547a0ea9d348de3fa
affected

778f3dd5a13c9e1642e0b2efea4b769387a70afa before 966f331403dc3ed04ff64eaf3930cf1267965e53
affected

778f3dd5a13c9e1642e0b2efea4b769387a70afa before 63b53198aff2e4e6c5866a4ff73c7891f958ffa4
affected

778f3dd5a13c9e1642e0b2efea4b769387a70afa before ede3e8ac90ae106f0b29cd759aadebc1568f1308
affected

778f3dd5a13c9e1642e0b2efea4b769387a70afa before 64dc7c68e040251d9ec6e989acb69f8f6ae4a10b
affected

778f3dd5a13c9e1642e0b2efea4b769387a70afa before 654b33ada4ab5e926cd9c570196fefa7bec7c1df
affected

Default status
affected

2.6.23
affected

Any version before 2.6.23
unaffected

5.10.236
unaffected

5.15.180
unaffected

6.1.132
unaffected

6.6.85
unaffected

6.12.21
unaffected

6.13.9
unaffected

6.14
unaffected

References

git.kernel.org/...c/eda279586e571b05dff44d48e05f8977ad05855d

git.kernel.org/...c/4b0b8445b6fd41e6f62ac90547a0ea9d348de3fa

git.kernel.org/...c/966f331403dc3ed04ff64eaf3930cf1267965e53

git.kernel.org/...c/63b53198aff2e4e6c5866a4ff73c7891f958ffa4

git.kernel.org/...c/ede3e8ac90ae106f0b29cd759aadebc1568f1308

git.kernel.org/...c/64dc7c68e040251d9ec6e989acb69f8f6ae4a10b

git.kernel.org/...c/654b33ada4ab5e926cd9c570196fefa7bec7c1df

cve.org (CVE-2025-21999)

nvd.nist.gov (CVE-2025-21999)

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