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libext2fs: fix tdb.c mmap leak 

When undoing an expansion of an mmap'd database while cancelling a
transaction, the tdb code prematurely decreases the variable that
tracks the file size, which leads to a region leak during the
subsequent unmap.  Fix this by maintaining a separate counter for the
region size.

(This is probably unnecessary since e2undo was the only user of tdb
transactions, but I suppose we could be proactive.)

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
crypto
Darrick J. Wong 2015-01-27 13:10:26 -05:00 committed by Theodore Ts'o
parent 2c741a8afc
commit 5f0164b3a4
1 changed files with 5 additions and 1 deletions
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6
lib/ext2fs/tdb.c
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@ -246,6 +246,7 @@ struct tdb_context {
int page_size;
int max_dead_records;
bool have_transaction_lock;
tdb_len_t real_map_size; /* how much space has been mapped */
};
@ -970,9 +971,10 @@ int tdb_munmap(struct tdb_context *tdb)
#ifdef HAVE_MMAP
if (tdb->map_ptr) {
int ret = munmap(tdb->map_ptr, tdb->map_size);
int ret = munmap(tdb->map_ptr, tdb->real_map_size);
if (ret != 0)
return ret;
tdb->real_map_size = 0;
}
#endif
tdb->map_ptr = NULL;
@ -995,10 +997,12 @@ void tdb_mmap(struct tdb_context *tdb)
*/
if (tdb->map_ptr == MAP_FAILED) {
tdb->real_map_size = 0;
tdb->map_ptr = NULL;
TDB_LOG((tdb, TDB_DEBUG_WARNING, "tdb_mmap failed for size %d (%s)\n",
tdb->map_size, strerror(errno)));
}
tdb->real_map_size = tdb->map_size;
} else {
tdb->map_ptr = NULL;
}