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Commit ecfcb85c authored by Tetsuo Handa's avatar Tetsuo Handa Committed by Greg Kroah-Hartman
Browse files

bfs: add sanity check at bfs_fill_super() 

commit 9f2df09a33aa2c76ce6385d382693f98d7f2f07e upstream.

syzbot is reporting too large memory allocation at bfs_fill_super() [1].
Since file system image is corrupted such that bfs_sb->s_start == 0,
bfs_fill_super() is trying to allocate 8MB of continuous memory. Fix
this by adding a sanity check on bfs_sb->s_start, __GFP_NOWARN and
printf().

[1] https://syzkaller.appspot.com/bug?id=16a87c236b951351374a84c8a32f40edbc034e96

Link: http://lkml.kernel.org/r/1525862104-3407-1-git-send-email-penguin-kernel@I-love.SAKURA.ne.jp


Signed-off-by: default avatarTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reported-by: default avatarsyzbot <syzbot+71c6b5d68e91149fc8a4@syzkaller.appspotmail.com>
Reviewed-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Cc: Tigran Aivazian <aivazian.tigran@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 47ff7629

fs/bfs/inode.c

+6 −3
Original line number Diff line number Diff line
@@ -350,7 +350,8 @@ static int bfs_fill_super(struct super_block *s, void *data, int silent) 


	s->s_magic = BFS_MAGIC;



	if (le32_to_cpu(bfs_sb->s_start) > le32_to_cpu(bfs_sb->s_end)) {

	if (le32_to_cpu(bfs_sb->s_start) > le32_to_cpu(bfs_sb->s_end) ||

	    le32_to_cpu(bfs_sb->s_start) < BFS_BSIZE) {

		printf("Superblock is corrupted\n");

		goto out1;

	}
@@ -359,9 +360,11 @@ static int bfs_fill_super(struct super_block *s, void *data, int silent) 
					sizeof(struct bfs_inode)

					+ BFS_ROOT_INO - 1;

	imap_len = (info->si_lasti / 8) + 1;

	info->si_imap = kzalloc(imap_len, GFP_KERNEL);

	if (!info->si_imap)

	info->si_imap = kzalloc(imap_len, GFP_KERNEL | __GFP_NOWARN);

	if (!info->si_imap) {

		printf("Cannot allocate %u bytes\n", imap_len);

		goto out1;

	}

	for (i = 0; i < BFS_ROOT_INO; i++)

		set_bit(i, info->si_imap);