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| author | Pi-Hsun Shih <pihsun@chromium.org> | 2019-03-13 11:44:33 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2019-03-14 14:36:20 -0700 |
| commit | a4046c06be50a4f01d435aa7fe57514818e6cc82 (patch) | |
| tree | 899cc993aa91e41a5c4578403e0d515a0c3bf4e2 /include/linux/swap.h | |
| parent | 17415606f9d8be06580cc0a873e27a6e4309ba2e (diff) | |
| download | lwn-a4046c06be50a4f01d435aa7fe57514818e6cc82.tar.gz lwn-a4046c06be50a4f01d435aa7fe57514818e6cc82.zip | |
include/linux/swap.h: use offsetof() instead of custom __swapoffset macro
Use offsetof() to calculate offset of a field to take advantage of
compiler built-in version when possible, and avoid UBSAN warning when
compiling with Clang:
UBSAN: Undefined behaviour in mm/swapfile.c:3010:38
member access within null pointer of type 'union swap_header'
CPU: 6 PID: 1833 Comm: swapon Tainted: G S 4.19.23 #43
Call trace:
dump_backtrace+0x0/0x194
show_stack+0x20/0x2c
__dump_stack+0x20/0x28
dump_stack+0x70/0x94
ubsan_epilogue+0x14/0x44
ubsan_type_mismatch_common+0xf4/0xfc
__ubsan_handle_type_mismatch_v1+0x34/0x54
__se_sys_swapon+0x654/0x1084
__arm64_sys_swapon+0x1c/0x24
el0_svc_common+0xa8/0x150
el0_svc_compat_handler+0x2c/0x38
el0_svc_compat+0x8/0x18
Link: http://lkml.kernel.org/r/20190312081902.223764-1-pihsun@chromium.org
Signed-off-by: Pi-Hsun Shih <pihsun@chromium.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/swap.h')
| -rw-r--r-- | include/linux/swap.h | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/include/linux/swap.h b/include/linux/swap.h index fc50e21b3b88..4bfb5c4ac108 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -157,9 +157,9 @@ struct swap_extent { /* * Max bad pages in the new format.. */ -#define __swapoffset(x) ((unsigned long)&((union swap_header *)0)->x) #define MAX_SWAP_BADPAGES \ - ((__swapoffset(magic.magic) - __swapoffset(info.badpages)) / sizeof(int)) + ((offsetof(union swap_header, magic.magic) - \ + offsetof(union swap_header, info.badpages)) / sizeof(int)) enum { SWP_USED = (1 << 0), /* is slot in swap_info[] used? */ |