From: Pedro Demarchi Gomes <pedrodemargomes@gmail.com> mainline inclusion from mainline-v6.19-rc1 commit d1693a7d5a38acf6424235a6070bcf5b186a360d category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/13378 CVE: CVE-2025-71067 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- When mounting, sb->s_blocksize is used to read the boot_block without being defined or validated. Set a dummy blocksize before attempting to read the boot_block. The issue can be triggered with the following syz reproducer: mkdirat(0xffffffffffffff9c, &(0x7f0000000080)='./file1\x00', 0x0) r4 = openat$nullb(0xffffffffffffff9c, &(0x7f0000000040), 0x121403, 0x0) ioctl$FS_IOC_SETFLAGS(r4, 0x40081271, &(0x7f0000000980)=0x4000) mount(&(0x7f0000000140)=@nullb, &(0x7f0000000040)='./cgroup\x00', &(0x7f0000000000)='ntfs3\x00', 0x2208004, 0x0) syz_clone(0x88200200, 0x0, 0x0, 0x0, 0x0, 0x0) Here, the ioctl sets the bdev block size to 16384. During mount, get_tree_bdev_flags() calls sb_set_blocksize(sb, block_size(bdev)), but since block_size(bdev) > PAGE_SIZE, sb_set_blocksize() leaves sb->s_blocksize at zero. Later, ntfs_init_from_boot() attempts to read the boot_block while sb->s_blocksize is still zero, which triggers the bug. Reported-by: syzbot+f4f84b57a01d6b8364ad@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=f4f84b57a01d6b8364ad Signed-off-by: Pedro Demarchi Gomes <pedrodemargomes@gmail.com> [almaz.alexandrovich@paragon-software.com: changed comment style, added return value handling] Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com> Conflicts: fs/ntfs3/super.c [Commit 6c3684e70383 ("ntfs: set dummy blocksize to read boot_block when mounting") add tag of read_boot in ntfs_init_from_boot().] Signed-off-by: Li Lingfeng <lilingfeng3@huawei.com> --- fs/ntfs3/super.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/fs/ntfs3/super.c b/fs/ntfs3/super.c index 1d6b45b70538..cbeb8156ff30 100644 --- a/fs/ntfs3/super.c +++ b/fs/ntfs3/super.c @@ -693,6 +693,11 @@ static int ntfs_init_from_boot(struct super_block *sb, u32 sector_size, sbi->volume.blocks = dev_size >> PAGE_SHIFT; + /* Set dummy blocksize to read boot_block. */ + if (!sb_min_blocksize(sb, PAGE_SIZE)) { + return -EINVAL; + } + bh = ntfs_bread(sb, 0); if (!bh) return -EIO; -- 2.52.0