From: Theodore Ts'o tytso@mit.edu

mainline inclusion from mainline-5.4-rc1 commit cd2d99229dc96219547e6349841e1aad851c6acc category: bugfix bugzilla: 50526 CVE: NA

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Originally, support for expanded timestamps had a bug in that pre-1970 times were erroneously encoded as being in the the 24th century. This was fixed in commit a4dad1ae24f8 ("ext4: Fix handling of extended tv_sec") which landed in 4.4. Starting with 4.4, pre-1970 timestamps were correctly encoded, but for backwards compatibility those incorrectly encoded timestamps were mapped back to the pre-1970 dates.

Given that backwards compatibility workaround has been around for 4 years, and given that running e2fsck from e2fsprogs 1.43.2 and later will offer to fix these timestamps (which has been released for 3 years), it's past time to drop the legacy workaround from the kernel.

Signed-off-by: Theodore Ts'o tytso@mit.edu Signed-off-by: Yu Kuai yukuai3@huawei.com Reviewed-by: zhangyi (F) yi.zhang@huawei.com Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- fs/ext4/ext4.h | 15 +-------------- 1 file changed, 1 insertion(+), 14 deletions(-)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index 2a63c69bd19e2..816d6a83d14be 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -835,21 +835,8 @@ static inline __le32 ext4_encode_extra_time(struct timespec64 *time) static inline void ext4_decode_extra_time(struct timespec64 *time, __le32 extra) { - if (unlikely(extra & cpu_to_le32(EXT4_EPOCH_MASK))) { - -#if 1 - /* Handle legacy encoding of pre-1970 dates with epoch - * 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 + if (unlikely(extra & cpu_to_le32(EXT4_EPOCH_MASK))) 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; }