From: Yury Norov <yury.norov@gmail.com>
To: Qian Cai <cai@lca.pw>, g@yury-thinkpad
Cc: Yuri Norov <ynorov@marvell.com>,
Andrey Konovalov <andreyknvl@google.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>
Subject: Re: "lib: rework bitmap_parse()" triggers invalid access errors
Date: Thu, 6 Jun 2019 18:57:37 -0700 [thread overview]
Message-ID: <20190607015737.GA11592@yury-thinkpad> (raw)
In-Reply-To: <1559837386.6132.47.camel@lca.pw>
On Thu, Jun 06, 2019 at 12:09:46PM -0400, Qian Cai wrote:
> On Wed, 2019-06-05 at 08:01 +0000, Yuri Norov wrote:
> > (Sorry for top-posting)
> >
> > I can reproduce this on next-20190604. Is it new trace, or like one you've
> > posted before?
>
> Same thing, "nbits" causes an invalid access.
>
> # ./scripts/faddr2line vmlinux bitmap_parse+0x20c/0x2d8
> bitmap_parse+0x20c/0x2d8:
> __bitmap_clear at lib/bitmap.c:280
> (inlined by) bitmap_clear at include/linux/bitmap.h:390
> (inlined by) bitmap_parse at lib/bitmap.c:662
>
> This line,
>
> while (len - bits_to_clear >= 0) {
[...]
The problem is in my code, and the fix is:
diff --git a/lib/bitmap.c b/lib/bitmap.c
index ebcf4700ebed..6b3e921f4e91 100644
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -664,7 +664,7 @@ int bitmap_parse(const char *start, unsigned int buflen,
unset_bit = (BITS_TO_U32(nmaskbits) - chunks) * 32;
if (unset_bit < nmaskbits) {
- bitmap_clear(maskp, unset_bit, nmaskbits);
+ bitmap_clear(maskp, unset_bit, nmaskbits - unset_bit);
return 0;
}
I'll add a test for this case and submit v3 soon.
Yury
prev parent reply other threads:[~2019-06-07 1:57 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-30 19:01 "lib: rework bitmap_parse()" triggers invalid access errors Qian Cai
2019-06-04 18:23 ` Qian Cai
[not found] ` <BN6PR1801MB20655CFFEA0CEA242C088C25CB160@BN6PR1801MB2065.namprd18.prod.outlook.com>
2019-06-06 16:09 ` Qian Cai
2019-06-07 1:57 ` Yury Norov [this message]
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