loop: Check for overflow while configuring loop
commit c490a0b5 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>
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a210408b
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