Sabyrzhan Tasbolatov df61d3cff4 fs/ext4: fix integer overflow in s_log_groups_per_flex
commit f91436d55a279f045987e8b8c1385585dca54be9 upstream.

syzbot found UBSAN: shift-out-of-bounds in ext4_mb_init [1], when
1 << sbi->s_es->s_log_groups_per_flex is bigger than UINT_MAX,
where sbi->s_mb_prefetch is unsigned integer type.

32 is the maximum allowed power of s_log_groups_per_flex. Following if
check will also trigger UBSAN shift-out-of-bound:

if (1 << sbi->s_es->s_log_groups_per_flex >= UINT_MAX) {

So I'm checking it against the raw number, perhaps there is another way
to calculate UINT_MAX max power. Also use min_t as to make sure it's
uint type.

[1] UBSAN: shift-out-of-bounds in fs/ext4/mballoc.c:2713:24
shift exponent 60 is too large for 32-bit type 'int'
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack+0x137/0x1be lib/dump_stack.c:120
 ubsan_epilogue lib/ubsan.c:148 [inline]
 __ubsan_handle_shift_out_of_bounds+0x432/0x4d0 lib/ubsan.c:395
 ext4_mb_init_backend fs/ext4/mballoc.c:2713 [inline]
 ext4_mb_init+0x19bc/0x19f0 fs/ext4/mballoc.c:2898
 ext4_fill_super+0xc2ec/0xfbe0 fs/ext4/super.c:4983

Reported-by: syzbot+a8b4b0c60155e87e9484@syzkaller.appspotmail.com
Signed-off-by: Sabyrzhan Tasbolatov <snovitoll@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20210224095800.3350002-1-snovitoll@gmail.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-03-30 14:32:08 +02:00
..
2020-10-16 11:11:22 -07:00
2021-03-20 10:43:43 +01:00
2020-11-19 22:38:29 -05:00
2020-09-10 14:03:31 -07:00
\n
2020-10-15 15:03:10 -07:00
2020-08-04 21:02:38 -04:00
2020-09-22 23:45:57 -04:00
2020-07-31 08:16:01 +02:00
2020-10-23 11:33:41 -07:00
2021-01-27 11:55:29 +01:00
2020-10-23 11:33:41 -07:00
2020-07-31 08:16:00 +02:00
2020-10-24 12:40:18 -07:00
2020-09-26 22:55:05 -04:00
2020-08-27 16:06:47 -04:00
2020-07-31 08:16:01 +02:00