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authorJan Kara <jack@suse.cz>2019-11-05 17:44:07 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-12-13 08:52:43 +0100
commit3152fcd479eeae2eeaa44b553adf05a1ccac7637 (patch)
treed31ca599c5fd3079eb48de035c07864aa3e5b1b8
parent18493bac1ae0fd613243c885503142559ec5f1ac (diff)
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jbd2: Fix possible overflow in jbd2_log_space_left()
commit add3efdd78b8a0478ce423bb9d4df6bd95e8b335 upstream. When number of free space in the journal is very low, the arithmetic in jbd2_log_space_left() could underflow resulting in very high number of free blocks and thus triggering assertion failure in transaction commit code complaining there's not enough space in the journal: J_ASSERT(journal->j_free > 1); Properly check for the low number of free blocks. CC: stable@vger.kernel.org Reviewed-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Jan Kara <jack@suse.cz> Link: https://lore.kernel.org/r/20191105164437.32602-1-jack@suse.cz Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--include/linux/jbd2.h4
1 files changed, 2 insertions, 2 deletions
diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
index 1cf1b9b8e975..268f3000d1b3 100644
--- a/include/linux/jbd2.h
+++ b/include/linux/jbd2.h
@@ -1587,7 +1587,7 @@ static inline int jbd2_space_needed(journal_t *journal)
static inline unsigned long jbd2_log_space_left(journal_t *journal)
{
/* Allow for rounding errors */
- unsigned long free = journal->j_free - 32;
+ long free = journal->j_free - 32;
if (journal->j_committing_transaction) {
unsigned long committing = atomic_read(&journal->
@@ -1596,7 +1596,7 @@ static inline unsigned long jbd2_log_space_left(journal_t *journal)
/* Transaction + control blocks */
free -= committing + (committing >> JBD2_CONTROL_BLOCKS_SHIFT);
}
- return free;
+ return max_t(long, free, 0);
}
/*