Bug 2493748 (CVE-2026-53311)

Summary: CVE-2026-53311 kernel: fuse: fix uninit-value in fuse_dentry_revalidate()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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Priority: low    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the FUSE (Filesystem in Userspace) subsystem of the Linux kernel. An uninitialized value vulnerability exists in the `fuse_dentry_revalidate()` function, where it may be called with a dentry that has an uninitialized `d_time` field. This can lead to unpredictable system behavior or a system crash, resulting in a Denial of Service (DoS).
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Description OSIDB Bzimport 2026-06-26 21:04:56 UTC 
In the Linux kernel, the following vulnerability has been resolved:

fuse: fix uninit-value in fuse_dentry_revalidate()

fuse_dentry_revalidate() may be called with a dentry that didn't had
->d_time initialised.  The issue was found with KMSAN, where lookup_open()
calls __d_alloc(), followed by d_revalidate(), as shown below:

=====================================================
BUG: KMSAN: uninit-value in fuse_dentry_revalidate+0x150/0x13d0 fs/fuse/dir.c:394
 fuse_dentry_revalidate+0x150/0x13d0 fs/fuse/dir.c:394
 d_revalidate fs/namei.c:1030 [inline]
 lookup_open fs/namei.c:4405 [inline]
 open_last_lookups fs/namei.c:4583 [inline]
 path_openat+0x1614/0x64c0 fs/namei.c:4827
 do_file_open+0x2aa/0x680 fs/namei.c:4859
[...]

Uninit was created at:
 slab_post_alloc_hook mm/slub.c:4466 [inline]
 slab_alloc_node mm/slub.c:4788 [inline]
 kmem_cache_alloc_lru_noprof+0x382/0x1280 mm/slub.c:4807
 __d_alloc+0x55/0xa00 fs/dcache.c:1740
 d_alloc_parallel+0x99/0x2740 fs/dcache.c:2604
 lookup_open fs/namei.c:4398 [inline]
 open_last_lookups fs/namei.c:4583 [inline]
 path_openat+0x135f/0x64c0 fs/namei.c:4827
 do_file_open+0x2aa/0x680 fs/namei.c:4859
[...]
=====================================================
Comment 1 Mauro Matteo Cascella 2026-06-29 08:44:33 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026062620-CVE-2026-53311-6a71@gregkh/T