linux-ext4 - [PATCH] e2fsck: do not read EA header beyond the end of an inode

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Message-Id: <1448565868-14893-1-git-send-email-artemiyv@acm.org>
Date:	Thu, 26 Nov 2015 19:24:28 +0000
From:	Artemiy Volkov <artemiyv@....org>
To:	linux-ext4@...r.kernel.org
Cc:	Artemiy Volkov <artemiyv@....org>
Subject: [PATCH] e2fsck: do not read EA header beyond the end of an inode

In check_inode_extra_space(), if we attempt to read an EA header at
the end of the extra space, in a corrupted filesystem it may result in
a read beyond the bounds of the inode. Add a check to prevent this.

Reproduced by running ./test_one --valgrind f_write_ea_toobig_extra_isize.

Signed-off-by: Artemiy Volkov <artemiyv@....org>
---
 e2fsck/pass1.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/e2fsck/pass1.c b/e2fsck/pass1.c
index 0a8e23e..f1c99ea 100644
--- a/e2fsck/pass1.c
+++ b/e2fsck/pass1.c
@@ -482,6 +482,10 @@ static void check_inode_extra_space(e2fsck_t ctx, struct problem_context *pctx)
                return;
        }

+        /* check if there is no place for an EA header */
+        if (inode->i_extra_isize >= max - sizeof(__u32))
+                return;
+
        eamagic = (__u32 *) (((char *) inode) + EXT2_GOOD_OLD_INODE_SIZE +
                        inode->i_extra_isize);
        if (*eamagic == EXT2_EXT_ATTR_MAGIC) {
-- 
2.6.2
--
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