linux-ext4 - [PATCH v2] e2fsck: do not read EA header beyond the end of an inode

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1448569394-27134-1-git-send-email-artemiyv@acm.org>
Date:	Thu, 26 Nov 2015 20:23:14 +0000
From:	Artemiy Volkov <artemiyv@....org>
To:	linux-ext4@...r.kernel.org
Cc:	Artemiy Volkov <artemiyv@....org>
Subject: [PATCH v2] 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>
---

A quick fix to v1 which wrongly uses spaces instead of tabs.

 e2fsck/pass1.c |    4 ++++
 1 file changed, 4 insertions(+)

diff --git a/e2fsck/pass1.c b/e2fsck/pass1.c
index 0a8e23e..71ea943 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_size >= max - sizeof(__u32))
+		return;
+
 	eamagic = (__u32 *) (((char *) inode) + EXT2_GOOD_OLD_INODE_SIZE +
 			inode->i_extra_isize);
 	if (*eamagic == EXT2_EXT_ATTR_MAGIC) {
-- 
1.7.10.4

--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html