From: Qian Cai <cai@lca.pw>
To: mpe@ellerman.id.au, akpm@linux-foundation.org
Cc: rashmicy@gmail.com, linux-mm@kvack.org,
linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
Qian Cai <cai@lca.pw>
Subject: [PATCH -next] powerpc/mm/ptdump: fix an undefined behaviour
Date: Wed, 4 Mar 2020 23:47:59 -0500 [thread overview]
Message-ID: <20200305044759.1279-1-cai@lca.pw> (raw)
Booting a power9 server with hash MMU could trigger an undefined
behaviour because pud_offset(p4d, 0) will do,
0 >> (PAGE_SHIFT:16 + PTE_INDEX_SIZE:8 + H_PMD_INDEX_SIZE:10)
UBSAN: shift-out-of-bounds in arch/powerpc/mm/ptdump/ptdump.c:282:15
shift exponent 34 is too large for 32-bit type 'int'
CPU: 6 PID: 1 Comm: swapper/0 Not tainted 5.6.0-rc4-next-20200303+ #13
Call Trace:
dump_stack+0xf4/0x164 (unreliable)
ubsan_epilogue+0x18/0x78
__ubsan_handle_shift_out_of_bounds+0x160/0x21c
walk_pagetables+0x2cc/0x700
walk_pud at arch/powerpc/mm/ptdump/ptdump.c:282
(inlined by) walk_pagetables at arch/powerpc/mm/ptdump/ptdump.c:311
ptdump_check_wx+0x8c/0xf0
mark_rodata_ro+0x48/0x80
kernel_init+0x74/0x194
ret_from_kernel_thread+0x5c/0x74
Fixes: 8eb07b187000 ("powerpc/mm: Dump linux pagetables")
Signed-off-by: Qian Cai <cai@lca.pw>
---
Notes for maintainers:
This is on the top of the linux-next commit "powerpc: add support for
folded p4d page tables" which is in the Andrew's tree.
arch/powerpc/mm/ptdump/ptdump.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/powerpc/mm/ptdump/ptdump.c b/arch/powerpc/mm/ptdump/ptdump.c
index 9d6256b61df3..b530f81398a7 100644
--- a/arch/powerpc/mm/ptdump/ptdump.c
+++ b/arch/powerpc/mm/ptdump/ptdump.c
@@ -279,7 +279,7 @@ static void walk_pmd(struct pg_state *st, pud_t *pud, unsigned long start)
static void walk_pud(struct pg_state *st, p4d_t *p4d, unsigned long start)
{
- pud_t *pud = pud_offset(p4d, 0);
+ pud_t *pud = pud_offset(p4d, 0UL);
unsigned long addr;
unsigned int i;
--
2.21.0 (Apple Git-122.2)
next reply other threads:[~2020-03-05 4:48 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-05 4:47 Qian Cai [this message]
2020-03-05 5:56 ` [PATCH -next] powerpc/mm/ptdump: fix an undefined behaviour Christophe Leroy
2020-03-05 6:53 ` Michael Ellerman
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200305044759.1279-1-cai@lca.pw \
--to=cai@lca.pw \
--cc=akpm@linux-foundation.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=mpe@ellerman.id.au \
--cc=rashmicy@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).