From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758328Ab3KMHAX (ORCPT ); Wed, 13 Nov 2013 02:00:23 -0500 Received: from caiajhbdcagg.dreamhost.com ([208.97.132.66]:46090 "EHLO homiemail-a75.g.dreamhost.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751383Ab3KMHAR (ORCPT ); Wed, 13 Nov 2013 02:00:17 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=novalis.org; h=message-id:subject :from:to:cc:date:in-reply-to:references:content-type :mime-version:content-transfer-encoding; q=dns; s=novalis.org; b=o6cpXJ71VHSIzkbZuAGv5keYPGxrfe5k7EQ6QGFh4TWumeNwZVANCuG242Do2 BdUe9s1Bd0SkJWnWUVGeSbf+0OCGPxb760nMfTjSvvuox5+a13hwCAM7p/YmYFDP k3Dae8/Gl2pcT2GVMYT1rb1WqAtAu8D5sJc/SHlkmzL8cU= Message-ID: <1384326015.8994.185.camel@chiang> Subject: [PATCH v4 1/2] ext4: Fix handling of extended tv_sec (bug 23732) From: David Turner To: Andreas Dilger Cc: "Theodore Ts'o" , Mark Harris , Jan Kara , Ext4 Developers List , Linux Kernel Mailing List Date: Wed, 13 Nov 2013 02:00:15 -0500 In-Reply-To: <6DE0AF86-98E6-4DE9-BB7F-40FB32E1BC26@dilger.ca> References: <1383808590.23882.13.camel@chiang> <20131107160341.GA3850@quack.suse.cz> <1383864864.23882.33.camel@chiang> <20131107231445.GG2054@quack.suse.cz> <1383866807.23882.41.camel@chiang> <1383981551.8994.27.camel@chiang> <1384070214.8994.47.camel@chiang> <20131112003018.GA30281@thunk.org> <6DE0AF86-98E6-4DE9-BB7F-40FB32E1BC26@dilger.ca> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.6.4-0ubuntu1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In ext4, the bottom two bits of {a,c,m}time_extra are used to extend the {a,c,m}time fields, deferring the year 2038 problem to the year 2446. When decoding these extended fields, for times whose bottom 32 bits would represent a negative number, sign extension causes the 64-bit extended timestamp to be negative as well, which is not what's intended. This patch corrects that issue, so that the only negative {a,c,m}times are those between 1901 and 1970 (as per 32-bit signed timestamps). Some older kernels might have written pre-1970 dates with 1,1 in the extra bits. This patch treats those incorrectly-encoded dates as pre-1970, instead of post-2311, until kernel 4.20 is released. Hopefully by then e2fsck will have fixed up the bad data. Signed-off-by: David Turner Reported-by: Mark Harris Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=23732 --- fs/ext4/ext4.h | 61 +++++++++++++++++++++++++++++++++++++--------------------- 1 file changed, 39 insertions(+), 22 deletions(-) diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index 18aa56b..7d5e019 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -26,6 +26,7 @@ #include #include #include +#include #include #include #include @@ -713,38 +714,54 @@ struct move_extent { sizeof((ext4_inode)->field)) \ <= (EXT4_GOOD_OLD_INODE_SIZE + \ (einode)->i_extra_isize)) \ + /* - * We use the bottom 34 bits of the signed 64-bit time value, with - * the top two of these bits in the bottom of extra. This leads - * to a slightly odd encoding, which works like this: + * We need is an encoding that preserves the times for extra epoch "00": * - * extra msb of - * epoch 32-bit - * bits time decoded 64-bit tv_sec valid time range - * 0 0 0 0x000000000..0x07fffffff 1970-01-01..2038-01-19 - * 0 0 1 0x080000000..0x0ffffffff 2038-01-19..2106-02-07 - * 0 1 0 0x100000000..0x17fffffff 2106-02-07..2174-02-25 - * 0 1 1 0x180000000..0x1ffffffff 2174-02-25..2242-03-16 - * 1 0 0 0x200000000..0x27fffffff 2242-03-16..2310-04-04 - * 1 0 1 0x280000000..0x2ffffffff 2310-04-04..2378-04-22 - * 1 1 0 0x300000000..0x37fffffff 2378-04-22..2446-05-10 - - * 1 1 1 -0x80000000..-0x00000001 1901-12-13..1969-12-31 + * extra msb of adjust for signed + * epoch 32-bit 32-bit tv_sec to + * bits time decoded 64-bit tv_sec 64-bit tv_sec valid time range + * 0 0 1 -0x80000000..-0x00000001 0x000000000 1901-12-13..1969-12-31 + * 0 0 0 0x000000000..0x07fffffff 0x000000000 1970-01-01..2038-01-19 + * 0 1 1 0x080000000..0x0ffffffff 0x100000000 2038-01-19..2106-02-07 + * 0 1 0 0x100000000..0x17fffffff 0x100000000 2106-02-07..2174-02-25 + * 1 0 1 0x180000000..0x1ffffffff 0x200000000 2174-02-25..2242-03-16 + * 1 0 0 0x200000000..0x27fffffff 0x200000000 2242-03-16..2310-04-04 + * 1 1 1 0x280000000..0x2ffffffff 0x300000000 2310-04-04..2378-04-22 + * 1 1 0 0x300000000..0x37fffffff 0x300000000 2378-04-22..2446-05-10 + * + * Note that previous versions of the kernel on 64-bit systems would + * incorrectly use extra epoch bits 1,1 for dates between 1901 and + * 1970. e2fsck will correct this, assuming that it is run on the + * affected filesystem before 2311. */ static inline __le32 ext4_encode_extra_time(struct timespec *time) { - return cpu_to_le32((sizeof(time->tv_sec) > 4 ? - (time->tv_sec >> 32) & EXT4_EPOCH_MASK : 0) | - ((time->tv_nsec << EXT4_EPOCH_BITS) & EXT4_NSEC_MASK)); + u32 extra = sizeof(time->tv_sec) > 4 ? + ((time->tv_sec - (s32)time->tv_sec) >> 32) & EXT4_EPOCH_MASK : 0; + return cpu_to_le32(extra | (time->tv_nsec << EXT4_EPOCH_BITS)); } static inline void ext4_decode_extra_time(struct timespec *time, __le32 extra) { - if (sizeof(time->tv_sec) > 4) - time->tv_sec |= (__u64)(le32_to_cpu(extra) & EXT4_EPOCH_MASK) - << 32; - time->tv_nsec = (le32_to_cpu(extra) & EXT4_NSEC_MASK) >> EXT4_EPOCH_BITS; + 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. + */ + u64 extra_bits = le32_to_cpu(extra) & EXT4_EPOCH_MASK; + if (extra_bits == 3) + 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; } #define EXT4_INODE_SET_XTIME(xtime, inode, raw_inode) \ -- 1.8.1.2