CVE - CVE-2024-47741

CVE-ID
CVE-2024-47741	Learn more at National Vulnerability Database (NVD) • CVSS Severity Rating • Fix Information • Vulnerable Software Versions • SCAP Mappings • CPE Information
Description
In the Linux kernel, the following vulnerability has been resolved: btrfs: fix race setting file private on concurrent lseek using same fd When doing concurrent lseek(2) system calls against the same file descriptor, using multiple threads belonging to the same process, we have a short time window where a race happens and can result in a memory leak. The race happens like this: 1) A program opens a file descriptor for a file and then spawns two threads (with the pthreads library for example), lets call them task A and task B; 2) Task A calls lseek with SEEK_DATA or SEEK_HOLE and ends up at file.c:find_desired_extent() while holding a read lock on the inode; 3) At the start of find_desired_extent(), it extracts the file's private_data pointer into a local variable named 'private', which has a value of NULL; 4) Task B also calls lseek with SEEK_DATA or SEEK_HOLE, locks the inode in shared mode and enters file.c:find_desired_extent(), where it also extracts file->private_data into its local variable 'private', which has a NULL value; 5) Because it saw a NULL file private, task A allocates a private structure and assigns to the file structure; 6) Task B also saw a NULL file private so it also allocates its own file private and then assigns it to the same file structure, since both tasks are using the same file descriptor. At this point we leak the private structure allocated by task A. Besides the memory leak, there's also the detail that both tasks end up using the same cached state record in the private structure (struct btrfs_file_private::llseek_cached_state), which can result in a use-after-free problem since one task can free it while the other is still using it (only one task took a reference count on it). Also, sharing the cached state is not a good idea since it could result in incorrect results in the future - right now it should not be a problem because it end ups being used only in extent-io-tree.c:count_range_bits() where we do range validation before using the cached state. Fix this by protecting the private assignment and check of a file while holding the inode's spinlock and keep track of the task that allocated the private, so that it's used only by that task in order to prevent user-after-free issues with the cached state record as well as potentially using it incorrectly in the future.
References
Note: References are provided for the convenience of the reader to help distinguish between vulnerabilities. The list is not intended to be complete.
MISC:https://git.kernel.org/stable/c/33d1310d4496e904123dab9c28b2d8d2c1800f97 URL:https://git.kernel.org/stable/c/33d1310d4496e904123dab9c28b2d8d2c1800f97 MISC:https://git.kernel.org/stable/c/7ee85f5515e86a4e2a2f51969795920733912bad URL:https://git.kernel.org/stable/c/7ee85f5515e86a4e2a2f51969795920733912bad MISC:https://git.kernel.org/stable/c/a412ca489ac27b9d0e603499315b7139c948130d URL:https://git.kernel.org/stable/c/a412ca489ac27b9d0e603499315b7139c948130d MISC:https://git.kernel.org/stable/c/f56a6d9c267ec7fa558ede7755551c047b1034cd URL:https://git.kernel.org/stable/c/f56a6d9c267ec7fa558ede7755551c047b1034cd
Assigning CNA
kernel.org
Date Record Created
20240930	Disclaimer: The record creation date may reflect when the CVE ID was allocated or reserved, and does not necessarily indicate when this vulnerability was discovered, shared with the affected vendor, publicly disclosed, or updated in CVE.
Phase (Legacy)
Assigned (20240930)
Votes (Legacy)

Comments (Legacy)

Proposed (Legacy)
N/A
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