Revision cdb281e63874086a650552d36c504ea717a0e0cb authored by Qi Zheng on 26 July 2022, 06:24:36 UTC, committed by Linus Torvalds on 26 July 2022, 16:21:43 UTC
The vmf->page can be NULL when the wp_page_reuse() is invoked by wp_pfn_shared(), it will cause the following panic: BUG: kernel NULL pointer dereference, address: 000000000000008 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP PTI CPU: 18 PID: 923 Comm: Xorg Not tainted 5.19.0-rc8.bm.1-amd64 #263 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g14 RIP: 0010:_compound_head+0x0/0x40 [...] Call Trace: wp_page_reuse+0x1c/0xa0 do_wp_page+0x1a5/0x3f0 __handle_mm_fault+0x8cf/0xd20 handle_mm_fault+0xd5/0x2a0 do_user_addr_fault+0x1d0/0x680 exc_page_fault+0x78/0x170 asm_exc_page_fault+0x22/0x30 To fix it, this patch performs a NULL pointer check before dereferencing the vmf->page. Fixes: 6c287605fd56 ("mm: remember exclusively mapped anonymous pages with PG_anon_exclusive") Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Reviewed-by: David Hildenbrand <david@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent e0dccc3
File | Mode | Size |
---|---|---|
Documentation | ||
LICENSES | ||
arch | ||
block | ||
certs | ||
crypto | ||
drivers | ||
fs | ||
include | ||
init | ||
ipc | ||
kernel | ||
lib | ||
mm | ||
net | ||
samples | ||
scripts | ||
security | ||
sound | ||
tools | ||
usr | ||
virt | ||
.clang-format | -rw-r--r-- | 19.8 KB |
.cocciconfig | -rw-r--r-- | 59 bytes |
.get_maintainer.ignore | -rw-r--r-- | 71 bytes |
.gitattributes | -rw-r--r-- | 62 bytes |
.gitignore | -rw-r--r-- | 1.9 KB |
.mailmap | -rw-r--r-- | 23.0 KB |
COPYING | -rw-r--r-- | 496 bytes |
CREDITS | -rw-r--r-- | 99.0 KB |
Kbuild | -rw-r--r-- | 1.3 KB |
Kconfig | -rw-r--r-- | 555 bytes |
MAINTAINERS | -rw-r--r-- | 653.4 KB |
Makefile | -rw-r--r-- | 64.1 KB |
README | -rw-r--r-- | 727 bytes |
Computing file changes ...