[PATCH AUTOSEL 6.1 10/28] fs/ntfs3: Correct function is_rst_area_valid

Sasha Levin
2024-02-13T00:22:48Z

From: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>

[ Upstream commit 1b7dd28e14c4728ae1a815605ca33ffb4ce1b309 ]

Reported-by: Robert Morris <rtm@csail.mit.edu>
Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/ntfs3/fslog.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/fs/ntfs3/fslog.c b/fs/ntfs3/fslog.c
index 710cb5aa5a65..d53ef128fa73 100644
--- a/fs/ntfs3/fslog.c
+++ b/fs/ntfs3/fslog.c
@@ -465,7 +465,7 @@ static inline bool is_rst_area_valid(const struct RESTART_HDR *rhdr)
{
const struct RESTART_AREA *ra;
u16 cl, fl, ul;
- u32 off, l_size, file_dat_bits, file_size_round;
+ u32 off, l_size, seq_bits;
u16 ro = le16_to_cpu(rhdr->ra_off);
u32 sys_page = le32_to_cpu(rhdr->sys_page_size);

@@ -511,13 +511,15 @@ static inline bool is_rst_area_valid(const struct RESTART_HDR *rhdr)
/* Make sure the sequence number bits match the log file size. */
l_size = le64_to_cpu(ra->l_size);

- file_dat_bits = sizeof(u64) * 8 - le32_to_cpu(ra->seq_num_bits);
- file_size_round = 1u << (file_dat_bits + 3);
- if (file_size_round != l_size &&
- (file_size_round < l_size || (file_size_round / 2) > l_size)) {
- return false;
+ seq_bits = sizeof(u64) * 8 + 3;
+ while (l_size) {
+ l_size >>= 1;
+ seq_bits -= 1;
}

+ if (seq_bits != ra->seq_num_bits)
+ return false;
+
/* The log page data offset and record header length must be quad-aligned. */
if (!IS_ALIGNED(le16_to_cpu(ra->data_off), 8) ||
!IS_ALIGNED(le16_to_cpu(ra->rec_hdr_len), 8))
--
2.43.0