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author | Amir Goldstein <amir73il@gmail.com> | 2022-08-16 16:53:17 +0200 |
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committer | Al Viro <viro@zeniv.linux.org.uk> | 2022-08-16 16:59:54 +0200 |
commit | d6da19c9cace63290ccfccb1fc35151ffefc0bec (patch) | |
tree | 00e66911e1e16675007d324b91572ab73adac346 /fs/reiserfs | |
parent | Linux 6.0-rc1 (diff) | |
download | linux-d6da19c9cace63290ccfccb1fc35151ffefc0bec.tar.xz linux-d6da19c9cace63290ccfccb1fc35151ffefc0bec.zip |
locks: fix TOCTOU race when granting write lease
Thread A trying to acquire a write lease checks the value of i_readcount
and i_writecount in check_conflicting_open() to verify that its own fd
is the only fd referencing the file.
Thread B trying to open the file for read will call break_lease() in
do_dentry_open() before incrementing i_readcount, which leaves a small
window where thread A can acquire the write lease and then thread B
completes the open of the file for read without breaking the write lease
that was acquired by thread A.
Fix this race by incrementing i_readcount before checking for existing
leases, same as the case with i_writecount.
Use a helper put_file_access() to decrement i_readcount or i_writecount
in do_dentry_open() and __fput().
Fixes: 387e3746d01c ("locks: eliminate false positive conflicts for write lease")
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/reiserfs')
0 files changed, 0 insertions, 0 deletions