[PATCH AUTOSEL 6.0 18/27] fs/ntfs3: Fix slab-out-of-bounds in r_page

Sasha Levin
2022-12-27T20:34:09Z

From: Yin Xiujiang <yinxiujiang@kylinos.cn>

[ Upstream commit ecfbd57cf9c5ca225184ae266ce44ae473792132 ]

When PAGE_SIZE is 64K, if read_log_page is called by log_read_rst for
the first time, the size of *buffer would be equal to
DefaultLogPageSize(4K).But for *buffer operations like memcpy,
if the memory area size(n) which being assigned to buffer is larger
than 4K (log->page_size(64K) or bytes(64K-page_off)), it will cause
an out of boundary error.
Call trace:
[...]
kasan_report+0x44/0x130
check_memory_region+0xf8/0x1a0
memcpy+0xc8/0x100
ntfs_read_run_nb+0x20c/0x460
read_log_page+0xd0/0x1f4
log_read_rst+0x110/0x75c
log_replay+0x1e8/0x4aa0
ntfs_loadlog_and_replay+0x290/0x2d0
ntfs_fill_super+0x508/0xec0
get_tree_bdev+0x1fc/0x34c
[...]

Fix this by setting variable r_page to NULL in log_read_rst.

Signed-off-by: Yin Xiujiang <yinxiujiang@kylinos.cn>
Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/ntfs3/fslog.c | 26 ++------------------------
1 file changed, 2 insertions(+), 24 deletions(-)

diff --git a/fs/ntfs3/fslog.c b/fs/ntfs3/fslog.c
index 138050b1aa93..4236194af35e 100644
--- a/fs/ntfs3/fslog.c
+++ b/fs/ntfs3/fslog.c
@@ -1132,7 +1132,7 @@ static int read_log_page(struct ntfs_log *log, u32 vbo,
return -EINVAL;

if (!*buffer) {
- to_free = kmalloc(bytes, GFP_NOFS);
+ to_free = kmalloc(log->page_size, GFP_NOFS);
if (!to_free)
return -ENOMEM;
*buffer = to_free;
@@ -1180,10 +1180,7 @@ static int log_read_rst(struct ntfs_log *log, u32 l_size, bool first,
struct restart_info *info)
{
u32 skip, vbo;
- struct RESTART_HDR *r_page = kmalloc(DefaultLogPageSize, GFP_NOFS);
-
- if (!r_page)
- return -ENOMEM;
+ struct RESTART_HDR *r_page = NULL;

/* Determine which restart area we are looking for. */
if (first) {
@@ -1197,7 +1194,6 @@ static int log_read_rst(struct ntfs_log *log, u32 l_size, bool first,
/* Loop continuously until we succeed. */
for (; vbo < l_size; vbo = 2 * vbo + skip, skip = 0) {
bool usa_error;
- u32 sys_page_size;
bool brst, bchk;
struct RESTART_AREA *ra;

@@ -1251,24 +1247,6 @@ static int log_read_rst(struct ntfs_log *log, u32 l_size, bool first,
goto check_result;
}

- /* Read the entire restart area. */
- sys_page_size = le32_to_cpu(r_page->sys_page_size);
- if (DefaultLogPageSize != sys_page_size) {
- kfree(r_page);
- r_page = kzalloc(sys_page_size, GFP_NOFS);
- if (!r_page)
- return -ENOMEM;
-
- if (read_log_page(log, vbo,
- (struct RECORD_PAGE_HDR **)&r_page,
- &usa_error)) {
- /* Ignore any errors. */
- kfree(r_page);
- r_page = NULL;
- continue;
- }
- }
-
if (is_client_area_valid(r_page, usa_error)) {
info->valid_page = true;
ra = Add2Ptr(r_page, le16_to_cpu(r_page->ra_off));
--
2.35.1