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Message-Id: <20210506185655.7118-1-mail@anirudhrb.com>
Date: Fri, 7 May 2021 00:26:54 +0530
From: Anirudh Rayabharam <mail@...rudhrb.com>
To: "Theodore Ts'o" <tytso@....edu>,
Andreas Dilger <adilger.kernel@...ger.ca>,
Dave Kleikamp <shaggy@...tin.ibm.com>,
Alex Tomas <alex@...sterfs.com>, Andrew Morton <akpm@...l.org>
Cc: gregkh@...uxfoundation.org,
linux-kernel-mentees@...ts.linuxfoundation.org,
Anirudh Rayabharam <mail@...rudhrb.com>,
syzbot+2dcfeaf8cb49b05e8f1a@...kaller.appspotmail.com,
linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2] ext4: fix kernel infoleak via ext4_extent_header
Initialize eh_generation of struct ext4_extent_header to prevent leaking
info to userspace. Fixes KMSAN kernel-infoleak bug reported by syzbot at:
http://syzkaller.appspot.com/bug?id=78e9ad0e6952a3ca16e8234724b2fa92d041b9b8
Reported-by: syzbot+2dcfeaf8cb49b05e8f1a@...kaller.appspotmail.com
Fixes: a86c61812637 ("[PATCH] ext3: add extent map support")
Signed-off-by: Anirudh Rayabharam <mail@...rudhrb.com>
---
Changes in v2:
Added a "Fixes:" tag.
v1: https://lore.kernel.org/lkml/20210505133011.32484-1-mail@anirudhrb.com/
---
fs/ext4/extents.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 77c84d6f1af6..677d4821bcc1 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -825,6 +825,7 @@ void ext4_ext_tree_init(handle_t *handle, struct inode *inode)
eh->eh_entries = 0;
eh->eh_magic = EXT4_EXT_MAGIC;
eh->eh_max = cpu_to_le16(ext4_ext_space_root(inode, 0));
+ eh->eh_generation = 0;
ext4_mark_inode_dirty(handle, inode);
}
@@ -1090,6 +1091,7 @@ static int ext4_ext_split(handle_t *handle, struct inode *inode,
neh->eh_max = cpu_to_le16(ext4_ext_space_block(inode, 0));
neh->eh_magic = EXT4_EXT_MAGIC;
neh->eh_depth = 0;
+ neh->eh_generation = 0;
/* move remainder of path[depth] to the new leaf */
if (unlikely(path[depth].p_hdr->eh_entries !=
@@ -1167,6 +1169,7 @@ static int ext4_ext_split(handle_t *handle, struct inode *inode,
neh->eh_magic = EXT4_EXT_MAGIC;
neh->eh_max = cpu_to_le16(ext4_ext_space_block_idx(inode, 0));
neh->eh_depth = cpu_to_le16(depth - i);
+ neh->eh_generation = 0;
fidx = EXT_FIRST_INDEX(neh);
fidx->ei_block = border;
ext4_idx_store_pblock(fidx, oldblock);
--
2.26.2
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