From: Pi-Hsun Shih <pihsun@chromium.org>
To: unlisted-recipients:; (no To-header on input)
Cc: Pi-Hsun Shih <pihsun@chromium.org>,
Andrew Morton <akpm@linux-foundation.org>,
Michal Hocko <mhocko@suse.com>,
Matthew Wilcox <willy@infradead.org>,
Johannes Weiner <hannes@cmpxchg.org>,
Vlastimil Babka <vbabka@suse.cz>,
Minchan Kim <minchan@kernel.org>, Omar Sandoval <osandov@fb.com>,
Huang Ying <ying.huang@intel.com>, Aaron Lu <aaron.lu@intel.com>,
Tejun Heo <tj@kernel.org>, Wei Yang <richard.weiyang@gmail.com>,
linux-kernel@vger.kernel.org (open list)
Subject: [PATCH] mm/swap: Avoid undefined behavior in __swapoffset
Date: Thu, 7 Mar 2019 17:46:50 +0800 [thread overview]
Message-ID: <20190307094653.119425-1-pihsun@chromium.org> (raw)
Use offsetof to calculate offset of a field to avoid UBSAN warning like:
===================================================================
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
==================================================================
Signed-off-by: Pi-Hsun Shih <pihsun@chromium.org>
---
include/linux/swap.h | 4 ++--
1 file 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? */
--
2.21.0.352.gf09ad66450-goog
next reply other threads:[~2019-03-07 9:47 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-07 9:46 Pi-Hsun Shih [this message]
2019-03-07 12:23 ` [PATCH] mm/swap: Avoid undefined behavior in __swapoffset Michal Hocko
2019-03-07 12:47 ` Pi-Hsun Shih
2019-03-07 13:23 ` Michal Hocko
2019-03-12 7:02 ` Pi-Hsun Shih
2019-03-12 8:07 ` Michal Hocko
2019-03-12 8:12 ` Pi-Hsun Shih
2019-03-12 8:18 ` [PATCH v2] mm/swap: Use offsetof instead of custom __swapoffset macro Pi-Hsun Shih
2019-03-12 8:26 ` Michal Hocko
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