Commit fa93ca18 authored by OGAWA Hirofumi's avatar OGAWA Hirofumi Committed by Linus Torvalds

fat: Fix _fat_bmap() race

fat_get_cluster() assumes the requested blocknr isn't truncated during
read. _fat_bmap() doesn't follow this rule.

This protects it by ->i_mutex.
Signed-off-by: default avatarOGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent dfc209c0
...@@ -199,7 +199,14 @@ static ssize_t fat_direct_IO(int rw, struct kiocb *iocb, ...@@ -199,7 +199,14 @@ static ssize_t fat_direct_IO(int rw, struct kiocb *iocb,
static sector_t _fat_bmap(struct address_space *mapping, sector_t block) static sector_t _fat_bmap(struct address_space *mapping, sector_t block)
{ {
return generic_block_bmap(mapping, block, fat_get_block); sector_t blocknr;
/* fat_get_cluster() assumes the requested blocknr isn't truncated. */
mutex_lock(&mapping->host->i_mutex);
blocknr = generic_block_bmap(mapping, block, fat_get_block);
mutex_unlock(&mapping->host->i_mutex);
return blocknr;
} }
static const struct address_space_operations fat_aops = { static const struct address_space_operations fat_aops = {
......
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