Messages in this thread Patch in this message | | | From | Chao Yu <> | Subject | [PATCH] f2fs: fix potential overflow in build_sit_info | Date | Wed, 9 Aug 2017 18:09:12 +0800 |
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On a 32-bit system, below calculation may overflow the 32-bit unsigned integer, allocating a buffer size that smaller than needed. A write on the buffer will then trigger an out of boundary write. 1. MAIN_SEGS(sbi) * sizeof(struct seg_entry) 2. MAIN_SECS(sbi) * sizeof(struct sec_entry)
Fixes this by doing type cast before calculating.
This patch fixes CVE-2017-10662.
Signed-off-by: Chao Yu <yuchao0@huawei.com> --- fs/f2fs/segment.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c index 682ae68b9ef7..947674b5f466 100644 --- a/fs/f2fs/segment.c +++ b/fs/f2fs/segment.c @@ -2997,8 +2997,9 @@ static int build_sit_info(struct f2fs_sb_info *sbi) SM_I(sbi)->sit_info = sit_i; - sit_i->sentries = kvzalloc(MAIN_SEGS(sbi) * - sizeof(struct seg_entry), GFP_KERNEL); + sit_i->sentries = kvzalloc((unsigned long long)MAIN_SEGS(sbi) * + (unsigned long long)sizeof(struct seg_entry), + GFP_KERNEL); if (!sit_i->sentries) return -ENOMEM; @@ -3036,8 +3037,10 @@ static int build_sit_info(struct f2fs_sb_info *sbi) return -ENOMEM; if (sbi->segs_per_sec > 1) { - sit_i->sec_entries = kvzalloc(MAIN_SECS(sbi) * - sizeof(struct sec_entry), GFP_KERNEL); + sit_i->sec_entries = kvzalloc( + (unsigned long long)MAIN_SECS(sbi) * + (unsigned long long)sizeof(struct sec_entry), + GFP_KERNEL); if (!sit_i->sec_entries) return -ENOMEM; } -- 2.13.1.388.g69e6b9b4f4a9
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