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authorDominique Martinet <asmadeus@codewreck.org>2024-05-21 21:13:36 +0900
committerDominique Martinet <asmadeus@codewreck.org>2024-05-23 20:29:09 +0900
commitc898afdc15645efb555acb6d85b484eb40a45409 (patch)
tree11d2e9cd376755b1df2cfd9e00d9af600ed1d8a0 /scripts/gdb/linux/mm.py
parent25460d6f39024cc3b8241b14c7ccf0d6f11a736a (diff)
9p: add missing locking around taking dentry fid list
Fix a use-after-free on dentry's d_fsdata fid list when a thread looks up a fid through dentry while another thread unlinks it: UAF thread: refcount_t: addition on 0; use-after-free. p9_fid_get linux/./include/net/9p/client.h:262 v9fs_fid_find+0x236/0x280 linux/fs/9p/fid.c:129 v9fs_fid_lookup_with_uid linux/fs/9p/fid.c:181 v9fs_fid_lookup+0xbf/0xc20 linux/fs/9p/fid.c:314 v9fs_vfs_getattr_dotl+0xf9/0x360 linux/fs/9p/vfs_inode_dotl.c:400 vfs_statx+0xdd/0x4d0 linux/fs/stat.c:248 Freed by: p9_fid_destroy (inlined) p9_client_clunk+0xb0/0xe0 linux/net/9p/client.c:1456 p9_fid_put linux/./include/net/9p/client.h:278 v9fs_dentry_release+0xb5/0x140 linux/fs/9p/vfs_dentry.c:55 v9fs_remove+0x38f/0x620 linux/fs/9p/vfs_inode.c:518 vfs_unlink+0x29a/0x810 linux/fs/namei.c:4335 The problem is that d_fsdata was not accessed under d_lock, because d_release() normally is only called once the dentry is otherwise no longer accessible but since we also call it explicitly in v9fs_remove that lock is required: move the hlist out of the dentry under lock then unref its fids once they are no longer accessible. Fixes: 154372e67d40 ("fs/9p: fix create-unlink-getattr idiom") Cc: stable@vger.kernel.org Reported-by: Meysam Firouzi Reported-by: Amirmohammad Eftekhar Reviewed-by: Christian Schoenebeck <linux_oss@crudebyte.com> Message-ID: <20240521122947.1080227-1-asmadeus@codewreck.org> Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
Diffstat (limited to 'scripts/gdb/linux/mm.py')
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