v2 --> v3:
Updated the commit message of patch 2/2 based on Alexander Viro's suggestion.
v1 -- > v2:
1. Replace INT_LIMIT(loff_t) with OFFSET_MAX in btrfs.
2. Replace INT_LIMIT() with type_max().
Zhen Lei (2):
btrfs: replace INT_LIMIT(loff_t) with OFFSET_MAX
fs: clear a UBSAN shift-out-of-bounds warning
fs/btrfs/ordered-data.c | 6 +++---
include/linux/fs.h | 5 ++---
2 files changed, 5 insertions(+), 6 deletions(-)
--
2.25.1
UBSAN: shift-out-of-bounds in fs/locks.c:2572:16
left shift of 1 by 63 places cannot be represented in type 'long long int'
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x8d/0xcf lib/dump_stack.c:106
ubsan_epilogue+0xa/0x44 lib/ubsan.c:151
__ubsan_handle_shift_out_of_bounds+0x1e7/0x208 lib/ubsan.c:322
locks_remove_posix+0xba/0x290 fs/locks.c:2572
filp_close+0x61/0xa0 fs/open.c:1424
close_fd+0x56/0x70 fs/file.c:664
__do_sys_close fs/open.c:1439 [inline]
__se_sys_close fs/open.c:1437 [inline]
__x64_sys_close+0x1a/0x50 fs/open.c:1437
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x34/0x80 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
</TASK>
INT_LIMIT() tries to do what type_max() does, except that type_max()
doesn't rely upon undefined behaviour, might as well use type_max()
instead.
Suggested-by: Eric Biggers <[email protected]>
Signed-off-by: Zhen Lei <[email protected]>
Reviewed-by: Eric Biggers <[email protected]>
---
include/linux/fs.h | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index e654435f16512c1..a384741b1449457 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1131,9 +1131,8 @@ struct file_lock_context {
/* The following constant reflects the upper bound of the file/locking space */
#ifndef OFFSET_MAX
-#define INT_LIMIT(x) (~((x)1 << (sizeof(x)*8 - 1)))
-#define OFFSET_MAX INT_LIMIT(loff_t)
-#define OFFT_OFFSET_MAX INT_LIMIT(off_t)
+#define OFFSET_MAX type_max(loff_t)
+#define OFFT_OFFSET_MAX type_max(off_t)
#endif
extern void send_sigio(struct fown_struct *fown, int fd, int band);
--
2.25.1
On Fri, Nov 25, 2022 at 05:13:56PM +0800, Zhen Lei wrote:
> v2 --> v3:
> Updated the commit message of patch 2/2 based on Alexander Viro's suggestion.
Not exactly what I meant... I've tentatively applied it, with the
following commit message:
--------------------------------
get rid of INT_LIMIT, use type_max() instead
INT_LIMIT() tries to do what type_max() does, except that type_max()
doesn't rely upon undefined behaviour[*], might as well use type_max()
instead.
[*] if T is an N-bit signed integer type, the maximal value in T is
pow(2, N - 1) - 1, all right, but naive expression for that value
ends up with a couple of wraparounds and as usual for wraparounds
in signed types, that's an undefined behaviour. type_max() takes
care to avoid those...
Caught-by: UBSAN
Suggested-by: Eric Biggers <[email protected]>
Signed-off-by: Zhen Lei <[email protected]>
Reviewed-by: Eric Biggers <[email protected]>
Signed-off-by: Al Viro <[email protected]>
--------------------------------
Does anybody have objections against the commit message above?
On 2022/11/26 5:00, Al Viro wrote:
> On Fri, Nov 25, 2022 at 05:13:56PM +0800, Zhen Lei wrote:
>> v2 --> v3:
>> Updated the commit message of patch 2/2 based on Alexander Viro's suggestion.
>
> Not exactly what I meant... I've tentatively applied it, with the
Haha, I felt like something was missing yesterday, too. But as far as my English
level is concerned, I usually copy the words suggested by others directly.
> following commit message:
Thanks.
>
> --------------------------------
> get rid of INT_LIMIT, use type_max() instead
>
> INT_LIMIT() tries to do what type_max() does, except that type_max()
> doesn't rely upon undefined behaviour[*], might as well use type_max()
> instead.
>
> [*] if T is an N-bit signed integer type, the maximal value in T is
> pow(2, N - 1) - 1, all right, but naive expression for that value
> ends up with a couple of wraparounds and as usual for wraparounds
> in signed types, that's an undefined behaviour. type_max() takes
> care to avoid those...
>
> Caught-by: UBSAN
> Suggested-by: Eric Biggers <[email protected]>
> Signed-off-by: Zhen Lei <[email protected]>
> Reviewed-by: Eric Biggers <[email protected]>
> Signed-off-by: Al Viro <[email protected]>
> --------------------------------
>
> Does anybody have objections against the commit message above?
Looks good to me.
>
> .
>
--
Regards,
Zhen Lei