From: Conrad Meyer Subject: [PATCH] fs: ext4: Sign-extend tv_sec after ORing in epoch bits Date: Sun, 30 Mar 2014 07:58:34 -0700 Message-ID: <1396191514-19081-1-git-send-email-cse.cem@gmail.com> Cc: linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, Conrad Meyer To: "Theodore Ts'o" , Andreas Dilger Return-path: Received: from mail-pd0-f179.google.com ([209.85.192.179]:62862 "EHLO mail-pd0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751025AbaC3O6p (ORCPT ); Sun, 30 Mar 2014 10:58:45 -0400 Received: by mail-pd0-f179.google.com with SMTP id w10so6902862pde.10 for ; Sun, 30 Mar 2014 07:58:44 -0700 (PDT) Sender: linux-ext4-owner@vger.kernel.org List-ID: Fixes kernel.org bug #23732. Background: ext4 stores time as a 34-bit quantity; 2 bits in some extra bits unneeded for nanoseconds in the inode, and 32 bits in the seconds field. On systems with 64-bit time_t, the EXT4_*INODE_GET_XTIME() code incorrectly sign-extended the low 32-bits of the seconds quantity before ORing in the 2 "epoch" bits from nanoseconds. This patch ORs in the 2 higher bits, then sign extends the 34-bit signed number to 64 bits. Signed-off-by: Conrad Meyer --- Patch against next-20140328. Note, the on-disk format has always been written correctly. It was just interpreted incorrectly. Repro: Before: $ touch -d 2038-01-31 test-123 $ sudo sh -c "echo 3 > /proc/sys/vm/drop_caches" $ ls -ld test-123 drwxrwxr-x 2 cmeyer cmeyer 4096 Dec 25 1901 test-123 After: $ ls -ld test-123 drwxrwxr-x 2 cmeyer cmeyer 4096 Jan 31 2038 test-123 Thanks! --- fs/ext4/ext4.h | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index f4f889e..07ee03d 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -710,6 +710,8 @@ struct move_extent { #define EXT4_EPOCH_BITS 2 #define EXT4_EPOCH_MASK ((1 << EXT4_EPOCH_BITS) - 1) #define EXT4_NSEC_MASK (~0UL << EXT4_EPOCH_BITS) +#define EXT4_EPOCH_SIGN (((1UL << (EXT4_EPOCH_BITS - 1)) << 16) << 16) +#define EXT4_SIGN_EXT (~((((1UL << EXT4_EPOCH_BITS) << 16) << 16) - 1)) /* * Extended fields will fit into an inode if the filesystem was formatted @@ -761,19 +763,23 @@ do { \ #define EXT4_INODE_GET_XTIME(xtime, inode, raw_inode) \ do { \ - (inode)->xtime.tv_sec = (signed)le32_to_cpu((raw_inode)->xtime); \ + (inode)->xtime.tv_sec = (__u64)le32_to_cpu((raw_inode)->xtime); \ if (EXT4_FITS_IN_INODE(raw_inode, EXT4_I(inode), xtime ## _extra)) \ ext4_decode_extra_time(&(inode)->xtime, \ raw_inode->xtime ## _extra); \ else \ (inode)->xtime.tv_nsec = 0; \ + if (sizeof((inode)->xtime.tv_sec) > 4) { \ + if ((inode)->xtime.tv_sec & EXT4_EPOCH_SIGN) \ + (inode)->xtime.tv_sec |= EXT4_SIGN_EXT; \ + } \ } while (0) #define EXT4_EINODE_GET_XTIME(xtime, einode, raw_inode) \ do { \ if (EXT4_FITS_IN_INODE(raw_inode, einode, xtime)) \ (einode)->xtime.tv_sec = \ - (signed)le32_to_cpu((raw_inode)->xtime); \ + (__u64)le32_to_cpu((raw_inode)->xtime); \ else \ (einode)->xtime.tv_sec = 0; \ if (EXT4_FITS_IN_INODE(raw_inode, einode, xtime ## _extra)) \ @@ -781,6 +787,10 @@ do { \ raw_inode->xtime ## _extra); \ else \ (einode)->xtime.tv_nsec = 0; \ + if (sizeof((einode)->xtime.tv_sec) > 4) { \ + if ((einode)->xtime.tv_sec & EXT4_EPOCH_SIGN) \ + (einode)->xtime.tv_sec |= EXT4_SIGN_EXT; \ + } \ } while (0) #define i_disk_version osd1.linux1.l_i_version -- 1.9.0