diff mbox series

[10/12] sata: sx4: fix pdc20621_get_from_dimm() on 64-bit

Message ID 20240326145348.3318887-1-arnd@kernel.org (mailing list archive)
State New, archived
Headers show
Series kbuild: enable some -Wextra warnings by default | expand

Commit Message

Arnd Bergmann March 26, 2024, 2:53 p.m. UTC 
From: Arnd Bergmann <arnd@arndb.de>

gcc warns about a memcpy() with overlapping pointers because of an
incorrect size calculation:

In file included from include/linux/string.h:369,
                 from drivers/ata/sata_sx4.c:66:
In function 'memcpy_fromio',
    inlined from 'pdc20621_get_from_dimm.constprop' at drivers/ata/sata_sx4.c:962:2:
include/linux/fortify-string.h:97:33: error: '__builtin_memcpy' accessing 4294934464 bytes at offsets 0 and [16, 16400] overlaps 6442385281 bytes at offset -2147450817 [-Werror=restrict]
   97 | #define __underlying_memcpy     __builtin_memcpy
      |                                 ^
include/linux/fortify-string.h:620:9: note: in expansion of macro '__underlying_memcpy'
  620 |         __underlying_##op(p, q, __fortify_size);                        \
      |         ^~~~~~~~~~~~~
include/linux/fortify-string.h:665:26: note: in expansion of macro '__fortify_memcpy_chk'
  665 | #define memcpy(p, q, s)  __fortify_memcpy_chk(p, q, s,                  \
      |                          ^~~~~~~~~~~~~~~~~~~~
include/asm-generic/io.h:1184:9: note: in expansion of macro 'memcpy'
 1184 |         memcpy(buffer, __io_virt(addr), size);
      |         ^~~~~~

The problem here is the overflow of an unsigned 32-bit number to a
negative that gets converted into a signed 'long', keeping a large
positive number.

Replace the complex calculation with a more readable min() variant
that avoids the warning.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/ata/sata_sx4.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

Comments

Damien Le Moal March 27, 2024, 1:36 a.m. UTC | #1 
On 3/26/24 23:53, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
> 
> gcc warns about a memcpy() with overlapping pointers because of an
> incorrect size calculation:
> 
> In file included from include/linux/string.h:369,
>                  from drivers/ata/sata_sx4.c:66:
> In function 'memcpy_fromio',
>     inlined from 'pdc20621_get_from_dimm.constprop' at drivers/ata/sata_sx4.c:962:2:
> include/linux/fortify-string.h:97:33: error: '__builtin_memcpy' accessing 4294934464 bytes at offsets 0 and [16, 16400] overlaps 6442385281 bytes at offset -2147450817 [-Werror=restrict]
>    97 | #define __underlying_memcpy     __builtin_memcpy
>       |                                 ^
> include/linux/fortify-string.h:620:9: note: in expansion of macro '__underlying_memcpy'
>   620 |         __underlying_##op(p, q, __fortify_size);                        \
>       |         ^~~~~~~~~~~~~
> include/linux/fortify-string.h:665:26: note: in expansion of macro '__fortify_memcpy_chk'
>   665 | #define memcpy(p, q, s)  __fortify_memcpy_chk(p, q, s,                  \
>       |                          ^~~~~~~~~~~~~~~~~~~~
> include/asm-generic/io.h:1184:9: note: in expansion of macro 'memcpy'
>  1184 |         memcpy(buffer, __io_virt(addr), size);
>       |         ^~~~~~
> 
> The problem here is the overflow of an unsigned 32-bit number to a
> negative that gets converted into a signed 'long', keeping a large
> positive number.
> 
> Replace the complex calculation with a more readable min() variant
> that avoids the warning.
> 
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")

That is old :)

> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Looks good to me. I can take the patch through libata tree, unless you prefer
taking the whole series ?

In case it is the latter:

Acked-by: Damien Le Moal <dlemoal@kernel.org>
Arnd Bergmann March 27, 2024, 8:21 p.m. UTC | #2 
On Wed, Mar 27, 2024, at 02:36, Damien Le Moal wrote:
> On 3/26/24 23:53, Arnd Bergmann wrote:
>
>> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
>
> Looks good to me. I can take the patch through libata tree, unless you prefer
> taking the whole series ?

Please merge it through your tree.

> In case it is the latter:
>
> Acked-by: Damien Le Moal <dlemoal@kernel.org>
>

Thanks,

    Arnd
Damien Le Moal March 28, 2024, 12:14 a.m. UTC | #3 
On 3/28/24 05:21, Arnd Bergmann wrote:
> On Wed, Mar 27, 2024, at 02:36, Damien Le Moal wrote:
>> On 3/26/24 23:53, Arnd Bergmann wrote:
>>
>>> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
>>
>> Looks good to me. I can take the patch through libata tree, unless you prefer
>> taking the whole series ?
> 
> Please merge it through your tree.

Applied to for-6.9-fixes with a fixed up patch title prefix ("ata: sata_sx4:
..."). Thanks !

> 
>> In case it is the latter:
>>
>> Acked-by: Damien Le Moal <dlemoal@kernel.org>
>>
> 
> Thanks,
> 
>     Arnd
diff mbox series

Patch

diff --git a/drivers/ata/sata_sx4.c b/drivers/ata/sata_sx4.c
index b51d7a9d0d90..a482741eb181 100644
--- a/drivers/ata/sata_sx4.c
+++ b/drivers/ata/sata_sx4.c
@@ -957,8 +957,7 @@  static void pdc20621_get_from_dimm(struct ata_host *host, void *psource,
 
 	offset -= (idx * window_size);
 	idx++;
-	dist = ((long) (window_size - (offset + size))) >= 0 ? size :
-		(long) (window_size - offset);
+	dist = min(size, window_size - offset);
 	memcpy_fromio(psource, dimm_mmio + offset / 4, dist);
 
 	psource += dist;
@@ -1005,8 +1004,7 @@  static void pdc20621_put_to_dimm(struct ata_host *host, void *psource,
 	readl(mmio + PDC_DIMM_WINDOW_CTLR);
 	offset -= (idx * window_size);
 	idx++;
-	dist = ((long)(s32)(window_size - (offset + size))) >= 0 ? size :
-		(long) (window_size - offset);
+	dist = min(size, window_size - offset);
 	memcpy_toio(dimm_mmio + offset / 4, psource, dist);
 	writel(0x01, mmio + PDC_GENERAL_CTLR);
 	readl(mmio + PDC_GENERAL_CTLR);