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Message-Id: <1396191514-19081-1-git-send-email-cse.cem@gmail.com>
Date: Sun, 30 Mar 2014 07:58:34 -0700
From: Conrad Meyer <cemeyer@...edu>
To: "Theodore Ts'o" <tytso@....edu>,
Andreas Dilger <adilger.kernel@...ger.ca>
Cc: linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org,
Conrad Meyer <cse.cem@...il.com>
Subject: [PATCH] fs: ext4: Sign-extend tv_sec after ORing in epoch bits
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 <cse.cem@...il.com>
---
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
--
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