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| author | Qian Cai <cai@lca.pw> | 2019-10-07 02:58:25 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2019-10-08 00:47:19 +0200 |
| commit | 234fdce892f905cbc2674349a9eb4873e288e5b3 (patch) | |
| tree | 1d960b4fef3ad98aa2ffd279af2340461120c7a9 /mm/page_alloc.c | |
| parent | mm/z3fold.c: claim page in the beginning of free (diff) | |
| download | linux-234fdce892f905cbc2674349a9eb4873e288e5b3.tar.xz linux-234fdce892f905cbc2674349a9eb4873e288e5b3.zip | |
mm/page_alloc.c: fix a crash in free_pages_prepare()
On architectures like s390, arch_free_page() could mark the page unused
(set_page_unused()) and any access later would trigger a kernel panic.
Fix it by moving arch_free_page() after all possible accessing calls.
Hardware name: IBM 2964 N96 400 (z/VM 6.4.0)
Krnl PSW : 0404e00180000000 0000000026c2b96e (__free_pages_ok+0x34e/0x5d8)
R:0 T:1 IO:0 EX:0 Key:0 M:1 W:0 P:0 AS:3 CC:2 PM:0 RI:0 EA:3
Krnl GPRS: 0000000088d43af7 0000000000484000 000000000000007c 000000000000000f
000003d080012100 000003d080013fc0 0000000000000000 0000000000100000
00000000275cca48 0000000000000100 0000000000000008 000003d080010000
00000000000001d0 000003d000000000 0000000026c2b78a 000000002717fdb0
Krnl Code: 0000000026c2b95c: ec1100b30659 risbgn %r1,%r1,0,179,6
0000000026c2b962: e32014000036 pfd 2,1024(%r1)
#0000000026c2b968: d7ff10001000 xc 0(256,%r1),0(%r1)
>0000000026c2b96e: 41101100 la %r1,256(%r1)
0000000026c2b972: a737fff8 brctg %r3,26c2b962
0000000026c2b976: d7ff10001000 xc 0(256,%r1),0(%r1)
0000000026c2b97c: e31003400004 lg %r1,832
0000000026c2b982: ebff1430016a asi 5168(%r1),-1
Call Trace:
__free_pages_ok+0x16a/0x5d8)
memblock_free_all+0x206/0x290
mem_init+0x58/0x120
start_kernel+0x2b0/0x570
startup_continue+0x6a/0xc0
INFO: lockdep is turned off.
Last Breaking-Event-Address:
__free_pages_ok+0x372/0x5d8
Kernel panic - not syncing: Fatal exception: panic_on_oops
00: HCPGIR450W CP entered; disabled wait PSW 00020001 80000000 00000000 26A2379C
In the past, only kernel_poison_pages() would trigger this but it needs
"page_poison=on" kernel cmdline, and I suspect nobody tested that on
s390. Recently, kernel_init_free_pages() (commit 6471384af2a6 ("mm:
security: introduce init_on_alloc=1 and init_on_free=1 boot options"))
was added and could trigger this as well.
[akpm@linux-foundation.org: add comment]
Link: http://lkml.kernel.org/r/1569613623-16820-1-git-send-email-cai@lca.pw
Fixes: 8823b1dbc05f ("mm/page_poison.c: enable PAGE_POISONING as a separate option")
Fixes: 6471384af2a6 ("mm: security: introduce init_on_alloc=1 and init_on_free=1 boot options")
Signed-off-by: Qian Cai <cai@lca.pw>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Alexander Duyck <alexander.duyck@gmail.com>
Cc: <stable@vger.kernel.org> [5.3+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/page_alloc.c')
| -rw-r--r-- | mm/page_alloc.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 15c2050c629b..c0b2e0306720 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1175,11 +1175,17 @@ static __always_inline bool free_pages_prepare(struct page *page, debug_check_no_obj_freed(page_address(page), PAGE_SIZE << order); } - arch_free_page(page, order); if (want_init_on_free()) kernel_init_free_pages(page, 1 << order); kernel_poison_pages(page, 1 << order, 0); + /* + * arch_free_page() can make the page's contents inaccessible. s390 + * does this. So nothing which can access the page's contents should + * happen after this. + */ + arch_free_page(page, order); + if (debug_pagealloc_enabled()) kernel_map_pages(page, 1 << order, 0); |