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From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Sasha Levin <sashal@kernel.org>, Siddh Raman Pant <code@siddh.me>,
	syzbot+a8e049cd3abd342936b6@syzkaller.appspotmail.com,
	Gao Xiang <hsiangkao@linux.alibaba.com>,
	linux-erofs@lists.ozlabs.org
Subject: [PATCH AUTOSEL 5.15 07/14] erofs/zmap.c: Fix incorrect offset calculation
Date: Tue, 24 Jan 2023 08:42:50 -0500	[thread overview]
Message-ID: <20230124134257.637523-7-sashal@kernel.org> (raw)
In-Reply-To: <20230124134257.637523-1-sashal@kernel.org>

From: Siddh Raman Pant <code@siddh.me>

[ Upstream commit 6acd87d50998ef0afafc441613aeaf5a8f5c9eff ]

Effective offset to add to length was being incorrectly calculated,
which resulted in iomap->length being set to 0, triggering a WARN_ON
in iomap_iter_done().

Fix that, and describe it in comments.

This was reported as a crash by syzbot under an issue about a warning
encountered in iomap_iter_done(), but unrelated to erofs.

C reproducer: https://syzkaller.appspot.com/text?tag=ReproC&x=1037a6b2880000
Kernel config: https://syzkaller.appspot.com/text?tag=KernelConfig&x=e2021a61197ebe02
Dashboard link: https://syzkaller.appspot.com/bug?extid=a8e049cd3abd342936b6

Reported-by: syzbot+a8e049cd3abd342936b6@syzkaller.appspotmail.com
Suggested-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Signed-off-by: Siddh Raman Pant <code@siddh.me>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20221209102151.311049-1-code@siddh.me
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/erofs/zmap.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/fs/erofs/zmap.c b/fs/erofs/zmap.c
index 7a6df35fdc91..73b86b5c1a75 100644
--- a/fs/erofs/zmap.c
+++ b/fs/erofs/zmap.c
@@ -700,12 +700,16 @@ static int z_erofs_iomap_begin_report(struct inode *inode, loff_t offset,
 		iomap->type = IOMAP_HOLE;
 		iomap->addr = IOMAP_NULL_ADDR;
 		/*
-		 * No strict rule how to describe extents for post EOF, yet
-		 * we need do like below. Otherwise, iomap itself will get
+		 * No strict rule on how to describe extents for post EOF, yet
+		 * we need to do like below. Otherwise, iomap itself will get
 		 * into an endless loop on post EOF.
+		 *
+		 * Calculate the effective offset by subtracting extent start
+		 * (map.m_la) from the requested offset, and add it to length.
+		 * (NB: offset >= map.m_la always)
 		 */
 		if (iomap->offset >= inode->i_size)
-			iomap->length = length + map.m_la - offset;
+			iomap->length = length + offset - map.m_la;
 	}
 	iomap->flags = 0;
 	return 0;
-- 
2.39.0


WARNING: multiple messages have this Message-ID (diff)
From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Siddh Raman Pant <code@siddh.me>,
	syzbot+a8e049cd3abd342936b6@syzkaller.appspotmail.com,
	Gao Xiang <hsiangkao@linux.alibaba.com>,
	Chao Yu <chao@kernel.org>, Sasha Levin <sashal@kernel.org>,
	xiang@kernel.org, linux-erofs@lists.ozlabs.org
Subject: [PATCH AUTOSEL 5.15 07/14] erofs/zmap.c: Fix incorrect offset calculation
Date: Tue, 24 Jan 2023 08:42:50 -0500	[thread overview]
Message-ID: <20230124134257.637523-7-sashal@kernel.org> (raw)
In-Reply-To: <20230124134257.637523-1-sashal@kernel.org>

From: Siddh Raman Pant <code@siddh.me>

[ Upstream commit 6acd87d50998ef0afafc441613aeaf5a8f5c9eff ]

Effective offset to add to length was being incorrectly calculated,
which resulted in iomap->length being set to 0, triggering a WARN_ON
in iomap_iter_done().

Fix that, and describe it in comments.

This was reported as a crash by syzbot under an issue about a warning
encountered in iomap_iter_done(), but unrelated to erofs.

C reproducer: https://syzkaller.appspot.com/text?tag=ReproC&x=1037a6b2880000
Kernel config: https://syzkaller.appspot.com/text?tag=KernelConfig&x=e2021a61197ebe02
Dashboard link: https://syzkaller.appspot.com/bug?extid=a8e049cd3abd342936b6

Reported-by: syzbot+a8e049cd3abd342936b6@syzkaller.appspotmail.com
Suggested-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Signed-off-by: Siddh Raman Pant <code@siddh.me>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Link: https://lore.kernel.org/r/20221209102151.311049-1-code@siddh.me
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/erofs/zmap.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/fs/erofs/zmap.c b/fs/erofs/zmap.c
index 7a6df35fdc91..73b86b5c1a75 100644
--- a/fs/erofs/zmap.c
+++ b/fs/erofs/zmap.c
@@ -700,12 +700,16 @@ static int z_erofs_iomap_begin_report(struct inode *inode, loff_t offset,
 		iomap->type = IOMAP_HOLE;
 		iomap->addr = IOMAP_NULL_ADDR;
 		/*
-		 * No strict rule how to describe extents for post EOF, yet
-		 * we need do like below. Otherwise, iomap itself will get
+		 * No strict rule on how to describe extents for post EOF, yet
+		 * we need to do like below. Otherwise, iomap itself will get
 		 * into an endless loop on post EOF.
+		 *
+		 * Calculate the effective offset by subtracting extent start
+		 * (map.m_la) from the requested offset, and add it to length.
+		 * (NB: offset >= map.m_la always)
 		 */
 		if (iomap->offset >= inode->i_size)
-			iomap->length = length + map.m_la - offset;
+			iomap->length = length + offset - map.m_la;
 	}
 	iomap->flags = 0;
 	return 0;
-- 
2.39.0


  parent reply	other threads:[~2023-01-24 13:43 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-24 13:42 [PATCH AUTOSEL 5.15 01/14] ARM: dts: imx: Fix pca9547 i2c-mux node name Sasha Levin
2023-01-24 13:42 ` Sasha Levin
2023-01-24 13:42 ` [PATCH AUTOSEL 5.15 02/14] ARM: dts: vf610: Fix pca9548 i2c-mux node names Sasha Levin
2023-01-24 13:42   ` Sasha Levin
2023-01-24 13:42 ` [PATCH AUTOSEL 5.15 03/14] arm64: dts: freescale: Fix pca954x " Sasha Levin
2023-01-24 13:42   ` Sasha Levin
2023-01-24 13:42 ` [PATCH AUTOSEL 5.15 04/14] arm64: dts: imx8mq-thor96: fix no-mmc property for SDHCI Sasha Levin
2023-01-24 13:42   ` Sasha Levin
2023-01-24 13:42 ` [PATCH AUTOSEL 5.15 05/14] firmware: arm_scmi: Clear stale xfer->hdr.status Sasha Levin
2023-01-24 13:42   ` Sasha Levin
2023-01-24 13:42 ` [PATCH AUTOSEL 5.15 06/14] bpf: Skip task with pid=1 in send_signal_common() Sasha Levin
2023-01-24 13:42 ` Sasha Levin [this message]
2023-01-24 13:42   ` [PATCH AUTOSEL 5.15 07/14] erofs/zmap.c: Fix incorrect offset calculation Sasha Levin
2023-01-24 13:42 ` [PATCH AUTOSEL 5.15 08/14] init/Kconfig: fix LOCALVERSION_AUTO help text Sasha Levin
2023-01-24 13:42 ` [PATCH AUTOSEL 5.15 09/14] btrfs: factor out scratching of one regular super block Sasha Levin
2023-01-24 13:44   ` Christoph Hellwig
2023-01-24 13:42 ` [PATCH AUTOSEL 5.15 10/14] blk-cgroup: fix missing pd_online_fn() while activating policy Sasha Levin
2023-01-24 13:42   ` Sasha Levin
2023-01-24 13:42 ` [PATCH AUTOSEL 5.15 11/14] HID: playstation: sanity check DualSense calibration data Sasha Levin
2023-01-24 13:42 ` [PATCH AUTOSEL 5.15 12/14] dmaengine: imx-sdma: Fix a possible memory leak in sdma_transfer_init Sasha Levin
2023-01-24 13:42   ` Sasha Levin
2023-01-24 13:42 ` [PATCH AUTOSEL 5.15 13/14] cifs: fix return of uninitialized rc in dfs_cache_update_tgthint() Sasha Levin
2023-01-24 13:42 ` [PATCH AUTOSEL 5.15 14/14] ext4: deal with legacy signed xattr name hash values Sasha Levin

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