[PATCH v2] mpt3sas: Avoid test/set_bit() operating in non-allocated memory

[PATCH v2] mpt3sas: Avoid test/set_bit() operating in non-allocated memory

[Breno Leitao]

There is a potential out-of-bounds access when using test_bit() on a
single word. The test_bit() and set_bit() functions operate on long
values, and when testing or setting a single word, they can exceed the
word boundary. KASAN detects this issue and produces a dump:

	 BUG: KASAN: slab-out-of-bounds in _scsih_add_device.constprop.0 (./arch/x86/include/asm/bitops.h:60 ./include/asm-generic/bitops/instrumented-atomic.h:29 drivers/scsi/mpt3sas/mpt3sas_scsih.c:7331) mpt3sas

	 Write of size 8 at addr ffff8881d26e3c60 by task kworker/u1536:2/2965

For full log, please look at [1].

Make the allocation at least the size of sizeof(unsigned long) so that
set_bit() and test_bit() have sufficient room for read/write operations
without overwriting unallocated memory.

[1] Link: https://lore.kernel.org/all/ZkNcALr3W3KGYYJG@gmail.com/

Fixes: c696f7b83ede ("scsi: mpt3sas: Implement device_remove_in_progress check in IOCTL path")
Cc: stable@vger.kernel.org
Suggested-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Breno Leitao <leitao@debian.org>
---
Changelog:

v2:
	* Do the same protection in krealloc() in
	  _base_check_ioc_facts_changes, as suggested by Keith.
---
 drivers/scsi/mpt3sas/mpt3sas_base.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/drivers/scsi/mpt3sas/mpt3sas_base.c b/drivers/scsi/mpt3sas/mpt3sas_base.c
index 258647fc6bdd..cc17204721c2 100644
--- a/drivers/scsi/mpt3sas/mpt3sas_base.c
+++ b/drivers/scsi/mpt3sas/mpt3sas_base.c
@@ -8512,6 +8512,12 @@ mpt3sas_base_attach(struct MPT3SAS_ADAPTER *ioc)
 	ioc->pd_handles_sz = (ioc->facts.MaxDevHandle / 8);
 	if (ioc->facts.MaxDevHandle % 8)
 		ioc->pd_handles_sz++;
+	/* pd_handles_sz should have, at least, the minimal room
+	 * for set_bit()/test_bit(), otherwise out-of-memory touch
+	 * may occur
+	 */
+	ioc->pd_handles_sz = ALIGN(ioc->pd_handles_sz, sizeof(unsigned long));
+
 	ioc->pd_handles = kzalloc(ioc->pd_handles_sz,
 	    GFP_KERNEL);
 	if (!ioc->pd_handles) {
@@ -8529,6 +8535,12 @@ mpt3sas_base_attach(struct MPT3SAS_ADAPTER *ioc)
 	ioc->pend_os_device_add_sz = (ioc->facts.MaxDevHandle / 8);
 	if (ioc->facts.MaxDevHandle % 8)
 		ioc->pend_os_device_add_sz++;
+
+	/* pend_os_device_add_sz should have, at least, the minimal room
+	 * for set_bit()/test_bit(), otherwise out-of-memory may occur
+	 */
+	ioc->pend_os_device_add_sz = ALIGN(ioc->pend_os_device_add_sz,
+					   sizeof(unsigned long));
 	ioc->pend_os_device_add = kzalloc(ioc->pend_os_device_add_sz,
 	    GFP_KERNEL);
 	if (!ioc->pend_os_device_add) {
@@ -8820,6 +8832,11 @@ _base_check_ioc_facts_changes(struct MPT3SAS_ADAPTER *ioc)
 		if (ioc->facts.MaxDevHandle % 8)
 			pd_handles_sz++;
 
+		/* pd_handles should have, at least, the minimal room
+		 * for set_bit()/test_bit(), otherwise out-of-memory touch
+		 * may occur
+		 */
+		pd_handles_sz = ALIGN(pd_handles_sz, sizeof(unsigned long));
 		pd_handles = krealloc(ioc->pd_handles, pd_handles_sz,
 		    GFP_KERNEL);
 		if (!pd_handles) {
-- 
2.43.0

Re: [PATCH v2] mpt3sas: Avoid test/set_bit() operating in non-allocated memory

[Keith Busch]

On Wed, Jun 05, 2024 at 01:55:29AM -0700, Breno Leitao wrote:
> There is a potential out-of-bounds access when using test_bit() on a
> single word. The test_bit() and set_bit() functions operate on long
> values, and when testing or setting a single word, they can exceed the
> word boundary. KASAN detects this issue and produces a dump:
> 
> 	 BUG: KASAN: slab-out-of-bounds in _scsih_add_device.constprop.0 (./arch/x86/include/asm/bitops.h:60 ./include/asm-generic/bitops/instrumented-atomic.h:29 drivers/scsi/mpt3sas/mpt3sas_scsih.c:7331) mpt3sas
> 
> 	 Write of size 8 at addr ffff8881d26e3c60 by task kworker/u1536:2/2965
> 
> For full log, please look at [1].
> 
> Make the allocation at least the size of sizeof(unsigned long) so that
> set_bit() and test_bit() have sufficient room for read/write operations
> without overwriting unallocated memory.

Looks good.

Reviewed-by: Keith Busch <kbusch@kernel.org>

Re: [PATCH v2] mpt3sas: Avoid test/set_bit() operating in non-allocated memory

[Martin K. Petersen]

On Wed, 05 Jun 2024 01:55:29 -0700, Breno Leitao wrote:

> There is a potential out-of-bounds access when using test_bit() on a
> single word. The test_bit() and set_bit() functions operate on long
> values, and when testing or setting a single word, they can exceed the
> word boundary. KASAN detects this issue and produces a dump:
> 
> 	 BUG: KASAN: slab-out-of-bounds in _scsih_add_device.constprop.0 (./arch/x86/include/asm/bitops.h:60 ./include/asm-generic/bitops/instrumented-atomic.h:29 drivers/scsi/mpt3sas/mpt3sas_scsih.c:7331) mpt3sas
> 
> [...]

Applied to 6.10/scsi-fixes, thanks!

[1/1] mpt3sas: Avoid test/set_bit() operating in non-allocated memory
      https://git.kernel.org/mkp/scsi/c/4254dfeda82f

-- 
Martin K. Petersen	Oracle Linux Engineering

RE: [PATCH v2] mpt3sas: Avoid test/set_bit() operating in non-allocated memory

[David Laight]

From: Breno Leitao <leitao@debian.org>
> Sent: 05 June 2024 09:55
> 
> There is a potential out-of-bounds access when using test_bit() on a
> single word. The test_bit() and set_bit() functions operate on long
> values, and when testing or setting a single word, they can exceed the
> word boundary. KASAN detects this issue and produces a dump:
> 
> 	 BUG: KASAN: slab-out-of-bounds in _scsih_add_device.constprop.0
> (./arch/x86/include/asm/bitops.h:60 ./include/asm-generic/bitops/instrumented-atomic.h:29
> drivers/scsi/mpt3sas/mpt3sas_scsih.c:7331) mpt3sas
> 
> 	 Write of size 8 at addr ffff8881d26e3c60 by task kworker/u1536:2/2965
> 
> For full log, please look at [1].
> 
> Make the allocation at least the size of sizeof(unsigned long) so that
> set_bit() and test_bit() have sufficient room for read/write operations
> without overwriting unallocated memory.
> 
...
> @@ -8512,6 +8512,12 @@ mpt3sas_base_attach(struct MPT3SAS_ADAPTER *ioc)
>  	ioc->pd_handles_sz = (ioc->facts.MaxDevHandle / 8);
>  	if (ioc->facts.MaxDevHandle % 8)
>  		ioc->pd_handles_sz++;
> +	/* pd_handles_sz should have, at least, the minimal room
> +	 * for set_bit()/test_bit(), otherwise out-of-memory touch
> +	 * may occur
> +	 */
> +	ioc->pd_handles_sz = ALIGN(ioc->pd_handles_sz, sizeof(unsigned long));
> +
>  	ioc->pd_handles = kzalloc(ioc->pd_handles_sz,
>  	    GFP_KERNEL);

That is entirely stupid code.
IIRC there is a BITMAP_SIZE() that does ((x) + 63u) & ~63)/8
(on 64bit systems).

	David

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