From a3b774342fa752a5290c0de36375289dfcf4a260 Mon Sep 17 00:00:00 2001 From: Randy Dunlap Date: Thu, 12 May 2022 20:38:37 -0700 Subject: fs/ntfs3: validate BOOT sectors_per_clusters When the NTFS BOOT sectors_per_clusters field is > 0x80, it represents a shift value. Make sure that the shift value is not too large before using it (NTFS max cluster size is 2MB). Return -EVINVAL if it too large. This prevents negative shift values and shift values that are larger than the field size. Prevents this UBSAN error: UBSAN: shift-out-of-bounds in ../fs/ntfs3/super.c:673:16 shift exponent -192 is negative Link: https://lkml.kernel.org/r/20220502175342.20296-1-rdunlap@infradead.org Fixes: 82cae269cfa9 ("fs/ntfs3: Add initialization of super block") Signed-off-by: Randy Dunlap Reported-by: syzbot+1631f09646bc214d2e76@syzkaller.appspotmail.com Reviewed-by: Namjae Jeon Cc: Konstantin Komarov Cc: Alexander Viro Cc: Kari Argillander Cc: Namjae Jeon Cc: Matthew Wilcox Signed-off-by: Andrew Morton --- fs/ntfs3/super.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) (limited to 'fs/ntfs3/super.c') diff --git a/fs/ntfs3/super.c b/fs/ntfs3/super.c index 278dcf502410..b2b54c4553f9 100644 --- a/fs/ntfs3/super.c +++ b/fs/ntfs3/super.c @@ -668,9 +668,11 @@ static u32 format_size_gb(const u64 bytes, u32 *mb) static u32 true_sectors_per_clst(const struct NTFS_BOOT *boot) { - return boot->sectors_per_clusters <= 0x80 - ? boot->sectors_per_clusters - : (1u << (0 - boot->sectors_per_clusters)); + if (boot->sectors_per_clusters <= 0x80) + return boot->sectors_per_clusters; + if (boot->sectors_per_clusters >= 0xf4) /* limit shift to 2MB max */ + return 1U << (0 - boot->sectors_per_clusters); + return -EINVAL; } /* @@ -713,6 +715,8 @@ static int ntfs_init_from_boot(struct super_block *sb, u32 sector_size, /* cluster size: 512, 1K, 2K, 4K, ... 2M */ sct_per_clst = true_sectors_per_clst(boot); + if ((int)sct_per_clst < 0) + goto out; if (!is_power_of_2(sct_per_clst)) goto out; -- cgit v1.2.3