Bug 2395684 (CVE-2023-53276)

Summary: CVE-2023-53276 kernel: Kernel: Denial of Service via ubifs memory leak
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Version: unspecifiedKeywords: Security
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OS: Linux   
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A flaw was found in the Linux kernel, specifically within its ubifs (Unsorted Block Image File System) component. When a temporary file is created on an encrypted directory, the system fails to properly free memory allocated for the filename. A local attacker could exploit this memory leak by repeatedly creating temporary files, which may lead to a denial of service (DoS) due to memory exhaustion, making the system unresponsive.
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Description OSIDB Bzimport 2025-09-16 09:03:19 UTC
In the Linux kernel, the following vulnerability has been resolved:

ubifs: Free memory for tmpfile name

When opening a ubifs tmpfile on an encrypted directory, function
fscrypt_setup_filename allocates memory for the name that is to be
stored in the directory entry, but after the name has been copied to the
directory entry inode, the memory is not freed.

When running kmemleak on it we see that it is registered as a leak. The
report below is triggered by a simple program 'tmpfile' just opening a
tmpfile:

  unreferenced object 0xffff88810178f380 (size 32):
    comm "tmpfile", pid 509, jiffies 4294934744 (age 1524.742s)
    backtrace:
      __kmem_cache_alloc_node
      __kmalloc
      fscrypt_setup_filename
      ubifs_tmpfile
      vfs_tmpfile
      path_openat

Free this memory after it has been copied to the inode.