From: Siddh Raman Pant code@siddh.me
mainline inclusion from mainline-v6.0-rc3 commit c490a0b5a4f36da3918181a8acdc6991d967c5f3 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I7JHOA CVE: NA
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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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=c620fe14aac810396d3c3edc9ad73848bf69a29...
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: Zhong Jinghua zhongjinghua@huawei.com Reviewed-by: Yu Kuai yukuai3@huawei.com Signed-off-by: Yongqiang Liu liuyongqiang13@huawei.com --- drivers/block/loop.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/drivers/block/loop.c b/drivers/block/loop.c index 303c123bf78c..69e986737111 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -1287,6 +1287,9 @@ loop_set_status(struct loop_device *lo, const struct loop_info64 *info) err = -EFBIG; goto out_unfreeze; } + /* loff_t vars have been assigned __u64 */ + if (lo->lo_offset < 0 || lo->lo_sizelimit < 0) + return -EOVERFLOW; }
loop_config_discard(lo);