Messages in this thread Patch in this message | | | From | Zhen Lei <> | Subject | [PATCH] fs: Clear a UBSAN shift-out-of-bounds warning | Date | Thu, 10 Nov 2022 11:10:24 +0800 |
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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'
Switch the calculation method to ((quarter - 1) * 2 + 1) can help us eliminate this false positive.
On the other hand, the old implementation has problems with char and short types, although not currently involved. printf("%d: %x\n", sizeof(char), INT_LIMIT(char)); printf("%d: %x\n", sizeof(short), INT_LIMIT(short)); 1: ffffff7f 2: ffff7fff
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com> --- include/linux/fs.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/linux/fs.h b/include/linux/fs.h index e654435f16512c1..88d42e2daed9f6c 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1131,7 +1131,7 @@ 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 INT_LIMIT(x) ((((x)1 << (sizeof(x) * 8 - 2)) - 1) * 2 + 1) #define OFFSET_MAX INT_LIMIT(loff_t) #define OFFT_OFFSET_MAX INT_LIMIT(off_t) #endif -- 2.25.1
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