Shifting signed 32-bit value by 31 bits is undefined, so changing most
significant bit to unsigned, and mark all of the flags as unsigned so
that we don't mix types. The UBSAN warning calltrace like below:
UBSAN: shift-out-of-bounds in fs/namespace.c:2330:33
left shift of 1 by 31 places cannot be represented in type 'int'
Call Trace:
<TASK>
dump_stack_lvl+0x7d/0xa5
dump_stack+0x15/0x1b
ubsan_epilogue+0xe/0x4e
__ubsan_handle_shift_out_of_bounds+0x1e7/0x20c
graft_tree+0x36/0xf0
do_add_mount+0x98/0x100
path_mount+0xbd6/0xd50
init_mount+0x6a/0xa3
devtmpfs_setup+0x47/0x7e
devtmpfsd+0x1a/0x50
kthread+0x126/0x160
ret_from_fork+0x1f/0x30
</TASK>
Fixes: e462ec50cb5f ("VFS: Differentiate mount flags (MS_*) from internal superblock flags")
Signed-off-by: Gaosheng Cui <cuigaosheng1@xxxxxxxxxx>
---
v3:
- convert SB_XX to (1U << n), keep a consistent code style, thanks!
v2:
- Mark all of the flags as unsigned instead of just one so that
- we don't mix types, and add the proper whitespaces around the
- shift operator everywhere, thanks!
include/linux/fs.h | 42 +++++++++++++++++++++---------------------
1 file changed, 21 insertions(+), 21 deletions(-)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index fa5ba1b1cbcd..7cd7bc761fa9 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1374,29 +1374,29 @@ extern int send_sigurg(struct fown_struct *fown);
* sb->s_flags. Note that these mirror the equivalent MS_* flags where
* represented in both.
*/
-#define SB_RDONLY 1 /* Mount read-only */
-#define SB_NOSUID 2 /* Ignore suid and sgid bits */
-#define SB_NODEV 4 /* Disallow access to device special files */
-#define SB_NOEXEC 8 /* Disallow program execution */
-#define SB_SYNCHRONOUS 16 /* Writes are synced at once */
-#define SB_MANDLOCK 64 /* Allow mandatory locks on an FS */
-#define SB_DIRSYNC 128 /* Directory modifications are synchronous */
-#define SB_NOATIME 1024 /* Do not update access times. */
-#define SB_NODIRATIME 2048 /* Do not update directory access times */
-#define SB_SILENT 32768
-#define SB_POSIXACL (1<<16) /* VFS does not apply the umask */
-#define SB_INLINECRYPT (1<<17) /* Use blk-crypto for encrypted files */
-#define SB_KERNMOUNT (1<<22) /* this is a kern_mount call */
-#define SB_I_VERSION (1<<23) /* Update inode I_version field */
-#define SB_LAZYTIME (1<<25) /* Update the on-disk [acm]times lazily */
+#define SB_RDONLY (1U) /* Mount read-only */
+#define SB_NOSUID (1U << 1) /* Ignore suid and sgid bits */
+#define SB_NODEV (1U << 2) /* Disallow access to device special files */
+#define SB_NOEXEC (1U << 3) /* Disallow program execution */
+#define SB_SYNCHRONOUS (1U << 4) /* Writes are synced at once */
+#define SB_MANDLOCK (1U << 6) /* Allow mandatory locks on an FS */
+#define SB_DIRSYNC (1U << 7) /* Directory modifications are synchronous */
+#define SB_NOATIME (1U << 10) /* Do not update access times. */
+#define SB_NODIRATIME (1U << 11) /* Do not update directory access times */
+#define SB_SILENT (1U << 15)
+#define SB_POSIXACL (1U << 16) /* VFS does not apply the umask */
+#define SB_INLINECRYPT (1U << 17) /* Use blk-crypto for encrypted files */
+#define SB_KERNMOUNT (1U << 22) /* this is a kern_mount call */
+#define SB_I_VERSION (1U << 23) /* Update inode I_version field */
+#define SB_LAZYTIME (1U << 25) /* Update the on-disk [acm]times lazily */
/* These sb flags are internal to the kernel */
-#define SB_SUBMOUNT (1<<26)
-#define SB_FORCE (1<<27)
-#define SB_NOSEC (1<<28)
-#define SB_BORN (1<<29)
-#define SB_ACTIVE (1<<30)
-#define SB_NOUSER (1<<31)
+#define SB_SUBMOUNT (1U << 26)
+#define SB_FORCE (1U << 27)
+#define SB_NOSEC (1U << 28)
+#define SB_BORN (1U << 29)
+#define SB_ACTIVE (1U << 30)
+#define SB_NOUSER (1U << 31)
/* These flags relate to encoding and casefolding */
#define SB_ENC_STRICT_MODE_FL (1 << 0)
--
2.25.1
