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| author | Siddh Raman Pant <code@siddh.me> | 2022-08-23 19:08:10 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-08-31 18:15:22 +0300 |
| commit | 6858933131d0dadac071c4d33335a9ea4b8e76cf (patch) | |
| tree | 774dcfed93c9c3beba30647d2851bd8244c81ad7 | |
| parent | 14cbbb9c9914663d0eeca6b59c1c9d4f5a547ee0 (diff) | |
| download | linux-6858933131d0dadac071c4d33335a9ea4b8e76cf.tar.xz | |
loop: Check for overflow while configuring loop
commit c490a0b5a4f36da3918181a8acdc6991d967c5f3 upstream.
The userspace can configure a loop using an ioctl call, wherein
a configuration of type loop_config is passed (see lo_ioctl()'s
case on line 1550 of drivers/block/loop.c). This proceeds to call
loop_configure() which in turn calls loop_set_status_from_info()
(see line 1050 of loop.c), passing &config->info which is of type
loop_info64*. This function then sets the appropriate values, like
the offset.
loop_device has lo_offset of type loff_t (see line 52 of loop.c),
which is typdef-chained to long long, whereas loop_info64 has
lo_offset of type __u64 (see line 56 of include/uapi/linux/loop.h).
The function directly copies offset from info to the device as
follows (See line 980 of loop.c):
lo->lo_offset = info->lo_offset;
This results in an overflow, which triggers a warning in iomap_iter()
due to a call to iomap_iter_done() which has:
WARN_ON_ONCE(iter->iomap.offset > iter->pos);
Thus, check for negative value during loop_set_status_from_info().
Bug report: https://syzkaller.appspot.com/bug?id=c620fe14aac810396d3c3edc9ad73848bf69a29e
Reported-and-tested-by: syzbot+a8e049cd3abd342936b6@syzkaller.appspotmail.com
Cc: stable@vger.kernel.org
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Siddh Raman Pant <code@siddh.me>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220823160810.181275-1-code@siddh.me
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | drivers/block/loop.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/drivers/block/loop.c b/drivers/block/loop.c index e4517d483bdc..b10410585a74 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -1031,6 +1031,11 @@ loop_set_status_from_info(struct loop_device *lo, lo->lo_offset = info->lo_offset; lo->lo_sizelimit = info->lo_sizelimit; + + /* loff_t vars have been assigned __u64 */ + if (lo->lo_offset < 0 || lo->lo_sizelimit < 0) + return -EOVERFLOW; + memcpy(lo->lo_file_name, info->lo_file_name, LO_NAME_SIZE); memcpy(lo->lo_crypt_name, info->lo_crypt_name, LO_NAME_SIZE); lo->lo_file_name[LO_NAME_SIZE-1] = 0; |