In the Linux kernel, the following vulnerability has been resolved:
ovl: support encoding fid from inode with no alias
Dmitry Safonov reported that a WARN_ON() assertion can be trigered by
userspace when calling inotify_show_fdinfo() for an overlayfs watched
inode, whose dentry aliases were discarded with drop_caches.
The WARN_ON() assertion in inotify_show_fdinfo() was removed, because
it is possible for encoding file handle to fail for other reason, but
the impact of failing to encode an overlayfs file handle goes beyond
this assertion.
As shown in the LTP test case mentioned in the link below, failure to
encode an overlayfs file handle from a non-aliased inode also leads to
failure to report an fid with FAN_DELETE_SELF fanotify events.
As Dmitry notes in his analyzis of the problem, ovl_encode_fh() fails
if it cannot find an alias for the inode, but this failure can be fixed.
ovl_encode_fh() seldom uses the alias and in the case of non-decodable
file handles, as is often the case with fanotify fid info,
ovl_encode_fh() never needs to use the alias to encode a file handle.
Defer finding an alias until it is actually needed so ovl_encode_fh()
will not fail in the common case of FAN_DELETE_SELF fanotify events.
Metrics
Affected Vendors & Products
References
History
Thu, 13 Feb 2025 01:00:00 +0000
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Tue, 21 Jan 2025 10:30:00 +0000
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Tue, 21 Jan 2025 03:15:00 +0000
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cvssV3_1
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Sun, 19 Jan 2025 10:30:00 +0000
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Description | In the Linux kernel, the following vulnerability has been resolved: ovl: support encoding fid from inode with no alias Dmitry Safonov reported that a WARN_ON() assertion can be trigered by userspace when calling inotify_show_fdinfo() for an overlayfs watched inode, whose dentry aliases were discarded with drop_caches. The WARN_ON() assertion in inotify_show_fdinfo() was removed, because it is possible for encoding file handle to fail for other reason, but the impact of failing to encode an overlayfs file handle goes beyond this assertion. As shown in the LTP test case mentioned in the link below, failure to encode an overlayfs file handle from a non-aliased inode also leads to failure to report an fid with FAN_DELETE_SELF fanotify events. As Dmitry notes in his analyzis of the problem, ovl_encode_fh() fails if it cannot find an alias for the inode, but this failure can be fixed. ovl_encode_fh() seldom uses the alias and in the case of non-decodable file handles, as is often the case with fanotify fid info, ovl_encode_fh() never needs to use the alias to encode a file handle. Defer finding an alias until it is actually needed so ovl_encode_fh() will not fail in the common case of FAN_DELETE_SELF fanotify events. | |
Title | ovl: support encoding fid from inode with no alias | |
References |
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Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2025-01-24T16:01:36.797Z
Reserved: 2024-12-29T08:45:45.729Z
Link: CVE-2025-21654
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No data.
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Status : Awaiting Analysis
Published: 2025-01-19T11:15:11.040
Modified: 2025-01-24T16:15:38.177
Link: CVE-2025-21654
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