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CVE-2025-38650

Description

In the Linux kernel, the following vulnerability has been resolved:hfsplus: remove mutex_lock check in hfsplus_free_extentsSyzbot reported an issue in hfsplus filesystem:------------[ cut here ]------------WARNING: CPU: 0 PID: 4400 at fs/hfsplus/extents.c:346 hfsplus_free_extents+0x700/0xad0Call Trace:hfsplus_file_truncate+0x768/0xbb0 fs/hfsplus/extents.c:606hfsplus_write_begin+0xc2/0xd0 fs/hfsplus/inode.c:56cont_expand_zero fs/buffer.c:2383 [inline]cont_write_begin+0x2cf/0x860 fs/buffer.c:2446hfsplus_write_begin+0x86/0xd0 fs/hfsplus/inode.c:52generic_cont_expand_simple+0x151/0x250 fs/buffer.c:2347hfsplus_setattr+0x168/0x280 fs/hfsplus/inode.c:263notify_change+0xe38/0x10f0 fs/attr.c:420do_truncate+0x1fb/0x2e0 fs/open.c:65do_sys_ftruncate+0x2eb/0x380 fs/open.c:193do_syscall_x64 arch/x86/entry/common.c:50 [inline]do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80entry_SYSCALL_64_after_hwframe+0x63/0xcdTo avoid deadlock, Commit 31651c607151 ("hfsplus: avoid deadlockon file truncation") unlock extree before hfsplus_free_extents(),and add check wheather extree is locked in hfsplus_free_extents().However, when operations such as hfsplus_file_release,hfsplus_setattr, hfsplus_unlink, and hfsplus_get_block are executedconcurrently in different files, it is very likely to trigger theWARN_ON, which will lead syzbot and xfstest to consider it as anabnormality.The comment above this warning also describes one of the easytriggering situations, which can easily trigger and causexfstest&syzbot to report errors.[task A] [task B]->hfsplus_file_release ->hfsplus_file_truncate ->hfs_find_init ->mutex_lock ->mutex_unlock ->hfsplus_write_begin ->hfsplus_get_block ->hfsplus_file_extend ->hfsplus_ext_read_extent ->hfs_find_init ->mutex_lock ->hfsplus_free_extents WARN_ON(mutex_is_locked) !!!Several threads could try to lock the shared extents tree.And warning can be triggered in one thread when another threadhas locked the tree. This is the wrong behavior of the code andwe need to remove the warning.

POC

Reference

No PoCs from references.

Github

- https://github.com/fkie-cad/nvd-json-data-feeds