Patch "nilfs2: fix failure to detect DAT corruption in btree and direct mappings" has been added to the 6.8-stable tree

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This is a note to let you know that I've just added the patch titled

    nilfs2: fix failure to detect DAT corruption in btree and direct mappings

to the 6.8-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     nilfs2-fix-failure-to-detect-dat-corruption-in-btree.patch
and it can be found in the queue-6.8 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit c7bf58475a269a6d7e799a80554b1b9d4e64f4d8
Author: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxx>
Date:   Wed Mar 13 19:58:26 2024 +0900

    nilfs2: fix failure to detect DAT corruption in btree and direct mappings
    
    [ Upstream commit f2f26b4a84a0ef41791bd2d70861c8eac748f4ba ]
    
    Patch series "nilfs2: fix kernel bug at submit_bh_wbc()".
    
    This resolves a kernel BUG reported by syzbot.  Since there are two
    flaws involved, I've made each one a separate patch.
    
    The first patch alone resolves the syzbot-reported bug, but I think
    both fixes should be sent to stable, so I've tagged them as such.
    
    This patch (of 2):
    
    Syzbot has reported a kernel bug in submit_bh_wbc() when writing file data
    to a nilfs2 file system whose metadata is corrupted.
    
    There are two flaws involved in this issue.
    
    The first flaw is that when nilfs_get_block() locates a data block using
    btree or direct mapping, if the disk address translation routine
    nilfs_dat_translate() fails with internal code -ENOENT due to DAT metadata
    corruption, it can be passed back to nilfs_get_block().  This causes
    nilfs_get_block() to misidentify an existing block as non-existent,
    causing both data block lookup and insertion to fail inconsistently.
    
    The second flaw is that nilfs_get_block() returns a successful status in
    this inconsistent state.  This causes the caller __block_write_begin_int()
    or others to request a read even though the buffer is not mapped,
    resulting in a BUG_ON check for the BH_Mapped flag in submit_bh_wbc()
    failing.
    
    This fixes the first issue by changing the return value to code -EINVAL
    when a conversion using DAT fails with code -ENOENT, avoiding the
    conflicting condition that leads to the kernel bug described above.  Here,
    code -EINVAL indicates that metadata corruption was detected during the
    block lookup, which will be properly handled as a file system error and
    converted to -EIO when passing through the nilfs2 bmap layer.
    
    Link: https://lkml.kernel.org/r/20240313105827.5296-1-konishi.ryusuke@xxxxxxxxx
    Link: https://lkml.kernel.org/r/20240313105827.5296-2-konishi.ryusuke@xxxxxxxxx
    Fixes: c3a7abf06ce7 ("nilfs2: support contiguous lookup of blocks")
    Signed-off-by: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxx>
    Reported-by: syzbot+cfed5b56649bddf80d6e@xxxxxxxxxxxxxxxxxxxxxxxxx
    Closes: https://syzkaller.appspot.com/bug?extid=cfed5b56649bddf80d6e
    Tested-by: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxx>
    Cc: <stable@xxxxxxxxxxxxxxx>
    Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/fs/nilfs2/btree.c b/fs/nilfs2/btree.c
index 13592e82eaf68..65659fa0372e6 100644
--- a/fs/nilfs2/btree.c
+++ b/fs/nilfs2/btree.c
@@ -724,7 +724,7 @@ static int nilfs_btree_lookup_contig(const struct nilfs_bmap *btree,
 		dat = nilfs_bmap_get_dat(btree);
 		ret = nilfs_dat_translate(dat, ptr, &blocknr);
 		if (ret < 0)
-			goto out;
+			goto dat_error;
 		ptr = blocknr;
 	}
 	cnt = 1;
@@ -743,7 +743,7 @@ static int nilfs_btree_lookup_contig(const struct nilfs_bmap *btree,
 			if (dat) {
 				ret = nilfs_dat_translate(dat, ptr2, &blocknr);
 				if (ret < 0)
-					goto out;
+					goto dat_error;
 				ptr2 = blocknr;
 			}
 			if (ptr2 != ptr + cnt || ++cnt == maxblocks)
@@ -781,6 +781,11 @@ static int nilfs_btree_lookup_contig(const struct nilfs_bmap *btree,
  out:
 	nilfs_btree_free_path(path);
 	return ret;
+
+ dat_error:
+	if (ret == -ENOENT)
+		ret = -EINVAL;  /* Notify bmap layer of metadata corruption */
+	goto out;
 }
 
 static void nilfs_btree_promote_key(struct nilfs_bmap *btree,
diff --git a/fs/nilfs2/direct.c b/fs/nilfs2/direct.c
index 4c85914f2abc3..893ab36824cc2 100644
--- a/fs/nilfs2/direct.c
+++ b/fs/nilfs2/direct.c
@@ -66,7 +66,7 @@ static int nilfs_direct_lookup_contig(const struct nilfs_bmap *direct,
 		dat = nilfs_bmap_get_dat(direct);
 		ret = nilfs_dat_translate(dat, ptr, &blocknr);
 		if (ret < 0)
-			return ret;
+			goto dat_error;
 		ptr = blocknr;
 	}
 
@@ -79,7 +79,7 @@ static int nilfs_direct_lookup_contig(const struct nilfs_bmap *direct,
 		if (dat) {
 			ret = nilfs_dat_translate(dat, ptr2, &blocknr);
 			if (ret < 0)
-				return ret;
+				goto dat_error;
 			ptr2 = blocknr;
 		}
 		if (ptr2 != ptr + cnt)
@@ -87,6 +87,11 @@ static int nilfs_direct_lookup_contig(const struct nilfs_bmap *direct,
 	}
 	*ptrp = ptr;
 	return cnt;
+
+ dat_error:
+	if (ret == -ENOENT)
+		ret = -EINVAL;  /* Notify bmap layer of metadata corruption */
+	return ret;
 }
 
 static __u64




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