linux-ext4 - [PATCH, resend] ext4: remove timebomb in ext4_decode_extra

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 for Android: free password hash cracker in your pocket

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

Message-Id: <20170821081115.2722-1-hch@lst.de>
Date:   Mon, 21 Aug 2017 10:11:15 +0200
From:   Christoph Hellwig <hch@....de>
To:     tytso@....edu, linux-ext4@...r.kernel.org
Subject: [PATCH, resend] ext4: remove timebomb in ext4_decode_extra_time()

Changing behavior based on the version code is a timebomb waiting to
happen, and not easily bisectable.  Drop it and leave any removal
to explicit developer action. (And I don't think file system
should _ever_ remove backwards compatibility that has no explicit
flag, but I'll leave that to the ext4 folks).

Signed-off-by: Christoph Hellwig <hch@....de>
Reviewed-by: Eric Biggers <ebiggers@...gle.com>
---

This was first sent on June 14, but kept getting ignored..

 fs/ext4/ext4.h | 12 +++---------
 1 file changed, 3 insertions(+), 9 deletions(-)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 32191548abed..d35749e7cf9f 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -838,21 +838,15 @@ static inline void ext4_decode_extra_time(struct timespec *time, __le32 extra)
 {
 	if (unlikely(sizeof(time->tv_sec) > 4 &&
 			(extra & cpu_to_le32(EXT4_EPOCH_MASK)))) {
-#if LINUX_VERSION_CODE < KERNEL_VERSION(4,20,0)
+
 		/* Handle legacy encoding of pre-1970 dates with epoch
-		 * bits 1,1.  We assume that by kernel version 4.20,
-		 * everyone will have run fsck over the affected
-		 * filesystems to correct the problem.  (This
-		 * backwards compatibility may be removed before this
-		 * time, at the discretion of the ext4 developers.)
+		 * bits 1,1. (This backwards compatibility may be removed
+		 * at the discretion of the ext4 developers.)
 		 */
 		u64 extra_bits = le32_to_cpu(extra) & EXT4_EPOCH_MASK;
 		if (extra_bits == 3 && ((time->tv_sec) & 0x80000000) != 0)
 			extra_bits = 0;
 		time->tv_sec += extra_bits << 32;
-#else
-		time->tv_sec += (u64)(le32_to_cpu(extra) & EXT4_EPOCH_MASK) << 32;
-#endif
 	}
 	time->tv_nsec = (le32_to_cpu(extra) & EXT4_NSEC_MASK) >> EXT4_EPOCH_BITS;
 }
-- 
2.11.0