From: Siddh Raman Pant via Linux-kernel-mentees <linux-kernel-mentees@lists.linuxfoundation.org> To: Jens Axboe <axboe@kernel.dk> Cc: linux-block <linux-block@vger.kernel.org>, syzbot+a8e049cd3abd342936b6@syzkaller.appspotmail.com, linux-kernel <linux-kernel@vger.kernel.org>, Matthew Wilcox <willy@infradead.org>, Christoph Hellwig <hch@infradead.org>, stable@vger.kernel.org, linux-kernel-mentees <linux-kernel-mentees@lists.linuxfoundation.org> Subject: [PATCH v2] loop: Check for overflow while configuring loop Date: Tue, 23 Aug 2022 21:38:10 +0530 [thread overview] Message-ID: <20220823160810.181275-1-code@siddh.me> (raw) 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> --- Changes since v1: - Do not break userspace API, so check loop_device for overflow. - Use EOVERFLOW instead of EINVAL. drivers/block/loop.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/block/loop.c b/drivers/block/loop.c index e3c0ba93c1a3..ad92192c7d61 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -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; -- 2.35.1 _______________________________________________ Linux-kernel-mentees mailing list Linux-kernel-mentees@lists.linuxfoundation.org https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees
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From: Siddh Raman Pant <code@siddh.me> To: Jens Axboe <axboe@kernel.dk> Cc: Matthew Wilcox <willy@infradead.org>, Christoph Hellwig <hch@infradead.org>, linux-block <linux-block@vger.kernel.org>, linux-kernel <linux-kernel@vger.kernel.org>, linux-kernel-mentees <linux-kernel-mentees@lists.linuxfoundation.org>, syzbot+a8e049cd3abd342936b6@syzkaller.appspotmail.com, stable@vger.kernel.org Subject: [PATCH v2] loop: Check for overflow while configuring loop Date: Tue, 23 Aug 2022 21:38:10 +0530 [thread overview] Message-ID: <20220823160810.181275-1-code@siddh.me> (raw) 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> --- Changes since v1: - Do not break userspace API, so check loop_device for overflow. - Use EOVERFLOW instead of EINVAL. drivers/block/loop.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/block/loop.c b/drivers/block/loop.c index e3c0ba93c1a3..ad92192c7d61 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -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; -- 2.35.1
next reply other threads:[~2022-08-23 16:08 UTC|newest] Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-08-23 16:08 Siddh Raman Pant via Linux-kernel-mentees [this message] 2022-08-23 16:08 ` [PATCH v2] loop: Check for overflow while configuring loop Siddh Raman Pant 2022-08-23 16:15 ` Christoph Hellwig 2022-08-23 16:15 ` Christoph Hellwig 2022-08-23 16:16 ` Jens Axboe 2022-08-23 16:16 ` Jens Axboe 2022-08-24 8:12 ` Siddh Raman Pant via Linux-kernel-mentees 2022-08-24 8:12 ` Siddh Raman Pant 2022-08-24 12:53 ` Jens Axboe 2022-08-24 12:53 ` Jens Axboe
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