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authorSahitya Tummala <stummala@codeaurora.org>2017-02-02 04:49:35 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-04-29 12:31:57 +0300
commitcff3a5f282ff1813352a146c487f4d8b472c250e (patch)
tree778c067a7896539997df33dda9de78cf4f57808e /tools/perf/util/dso.c
parentff738afb8a847414f73b729cb25df624bd743089 (diff)
downloadlinux-cff3a5f282ff1813352a146c487f4d8b472c250e.tar.xz
jbd2: fix use after free in kjournald2()
commit dbfcef6b0f4012c57bc0b6e0e660d5ed12a5eaed upstream. Below is the synchronization issue between unmount and kjournald2 contexts, which results into use after free issue in kjournald2(). Fix this issue by using journal->j_state_lock to synchronize the wait_event() done in journal_kill_thread() and the wake_up() done in kjournald2(). TASK 1: umount cmd: |--jbd2_journal_destroy() { |--journal_kill_thread() { write_lock(&journal->j_state_lock); journal->j_flags |= JBD2_UNMOUNT; ... write_unlock(&journal->j_state_lock); wake_up(&journal->j_wait_commit); TASK 2 wakes up here: kjournald2() { ... checks JBD2_UNMOUNT flag and calls goto end-loop; ... end_loop: write_unlock(&journal->j_state_lock); journal->j_task = NULL; --> If this thread gets pre-empted here, then TASK 1 wait_event will exit even before this thread is completely done. wait_event(journal->j_wait_done_commit, journal->j_task == NULL); ... write_lock(&journal->j_state_lock); write_unlock(&journal->j_state_lock); } |--kfree(journal); } } wake_up(&journal->j_wait_done_commit); --> this step now results into use after free issue. } Signed-off-by: Sahitya Tummala <stummala@codeaurora.org> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Cc: Amit Pundir <amit.pundir@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'tools/perf/util/dso.c')
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