From: Kees Cook <keescook@chromium.org>
To: Nick Desaulniers <ndesaulniers@google.com>
Cc: Jeffrin Thalakkottoor <jeffrin@rajagiritech.edu.in>,
Steven Rostedt <rostedt@goodmis.org>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
tobin@kernel.org, lkml <linux-kernel@vger.kernel.org>,
Dmitry Vyukov <dvyukov@google.com>,
Alexander Potapenko <glider@google.com>
Subject: Re: BUG: KASAN: global-out-of-bounds in ata_exec_internal_sg+0x50f/0xc70
Date: Thu, 18 Jul 2019 14:35:45 -0700 [thread overview]
Message-ID: <201907181423.E808958@keescook> (raw)
In-Reply-To: <CAKwvOdmg2b2PMzuzNmutacFArBNagjtwG=_VZvKhb4okzSkdiA@mail.gmail.com>
On Tue, Jul 16, 2019 at 11:28:29AM -0700, Nick Desaulniers wrote:
> On Wed, Jul 10, 2019 at 10:44 AM Jeffrin Thalakkottoor
> <jeffrin@rajagiritech.edu.in> wrote:
> >
> > hello all ,
> >
> > i encountered a KASAN bug related . here are some related information...
> >
> >
> > -------------------x-----------------------------x------------------
> > [ 30.037312] BUG: KASAN: global-out-of-bounds in
> > ata_exec_internal_sg+0x50f/0xc70
> > [ 30.037447] Read of size 16 at addr ffffffff91f41f80 by task scsi_eh_1/149
> >
> >
> > [ 30.039935] The buggy address belongs to the variable:
> > [ 30.040059] cdb.48319+0x0/0x40
> > (gdb) l *ata_exec_internal_sg+0x50f
> > 0xffffffff81c7b59f is in ata_exec_internal_sg (./include/linux/string.h:359).
>
> So looks like ata_exec_internal_sg() is panic'ing when...
>
> > 354 if (q_size < size)
> > 355 __read_overflow2();
> > 356 }
> > 357 if (p_size < size || q_size < size)
> > 358 fortify_panic(__func__);
> > 359 return __builtin_memcpy(p, q, size);
^^^ here, so within memcpy(), but after the "easy" sanity checks.
The only place where I see ata_exec_internal_sg() calling memcpy() is
here:
/* prepare & issue qc */
qc->tf = *tf;
if (cdb)
memcpy(qc->cdb, cdb, ATAPI_CDB_LEN);
the "16" is consistent with the report:
include/linux/ata.h: ATAPI_CDB_LEN = 16,
which matches the claim about the cdb variable from KASAN. And it's a
read, so "cdb" is wrong. Do you have a longer back trace? What called
ata_exec_internal_sg()?
ata_exec_internal() is the only caller of ata_exec_internal_sg(). Nearly
all callers of ata_exec_internal() pass a NULL cdb. Those that don't
are:
atapi_eh_tur()
u8 cdb[ATAPI_CDB_LEN] = ...
atapi_eh_request_sense()
u8 cdb[ATAPI_CDB_LEN] = ...
These two are on the static and correctly sized.
eject_tray()
static const char cdb[ATAPI_CDB_LEN] = ...
zpodd_get_mech_type()
static const char cdb[] = ...
These are both in rodata, and only the first is correctly sized. I
assume the following will fix it:
diff --git a/drivers/ata/libata-zpodd.c b/drivers/ata/libata-zpodd.c
index 173e6f2dd9af..eefda51f97d3 100644
--- a/drivers/ata/libata-zpodd.c
+++ b/drivers/ata/libata-zpodd.c
@@ -56,7 +56,7 @@ static enum odd_mech_type zpodd_get_mech_type(struct ata_device *dev)
unsigned int ret;
struct rm_feature_desc *desc;
struct ata_taskfile tf;
- static const char cdb[] = { GPCMD_GET_CONFIGURATION,
+ static const char cdb[ATAPI_CDB_LEN] = { GPCMD_GET_CONFIGURATION,
2, /* only 1 feature descriptor requested */
0, 3, /* 3, removable medium feature */
0, 0, 0,/* reserved */
--
Kees Cook
next prev parent reply other threads:[~2019-07-18 21:35 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-10 17:44 BUG: KASAN: global-out-of-bounds in ata_exec_internal_sg+0x50f/0xc70 Jeffrin Thalakkottoor
2019-07-16 18:28 ` Nick Desaulniers
2019-07-16 18:57 ` Steven Rostedt
2019-07-16 19:45 ` Nick Desaulniers
2019-07-18 21:35 ` Kees Cook [this message]
2019-07-29 19:34 ` Jeffrin Thalakkottoor
2019-07-29 19:55 ` Jens Axboe
2019-07-29 20:13 ` Jeffrin Thalakkottoor
2019-07-25 21:34 ` Jeffrin Thalakkottoor
-- strict thread matches above, loose matches on Subject: below --
2019-06-13 18:36 Jeffrin Thalakkottoor
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