On Tue, 13 Nov 2018 at 05:52, Sasha Levin sashal@kernel.org wrote:
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=16a87c236b951351374a84c8a32f40edbc034e9...
Hi Sasha,
Thank you, but no, I am rejecting this patch as I have already submitted a much more robust and accurate (stronger check) patch to Andrew Morton a couple of days ago against 4.20-rc1. Andrew, if you would like me to make the same patch against 4.19.1 as well, please let me know.
Kind regards, Tigran
Link: http://lkml.kernel.org/r/1525862104-3407-1-git-send-email-penguin-kernel@I-l... Signed-off-by: Tetsuo Handa penguin-kernel@I-love.SAKURA.ne.jp Reported-by: syzbot syzbot+71c6b5d68e91149fc8a4@syzkaller.appspotmail.com Reviewed-by: Andrew Morton akpm@linux-foundation.org Cc: Tigran Aivazian aivazian.tigran@gmail.com Cc: Matthew Wilcox willy@infradead.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Sasha Levin sashal@kernel.org
fs/bfs/inode.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/fs/bfs/inode.c b/fs/bfs/inode.c index 90bc079d9982..0ee38b284ad7 100644 --- a/fs/bfs/inode.c +++ b/fs/bfs/inode.c @@ -349,7 +349,8 @@ 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; }@@ -358,9 +359,11 @@ 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);-- 2.17.1