BackPup/Linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-09-25 21:21:09 -04:00
Code Issues Packages Projects Releases Wiki Activity

loop: Check for overflow while configuring loop

Browse Source 
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: [email protected]
Cc: [email protected]
Reviewed-by: Matthew Wilcox (Oracle) <[email protected]>
Signed-off-by: Siddh Raman Pant <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>
This commit is contained in:
Siddh Raman Pant
2022-08-24 06:52:52 -06:00
committed by Jens Axboe
parent 65fac0d54f
commit c490a0b5a4
1 changed files with 5 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files
drivers/block/loop.c
+5
View File
@@ -979,6 +979,11 @@ 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);
lo->lo_file_name[LO_NAME_SIZE-1] = 0;
lo->lo_flags = info->lo_flags;