From: Arnd Bergmann <arnd@arndb.de>
gcc-11 points out a potential issue with integer overflow when
the iwl_dev_info_table[] array is empty:
drivers/net/wireless/intel/iwlwifi/pcie/drv.c:1344:42: error: implicit conversion from 'unsigned long' to 'int' changes value from 18446744073709551615 to -1 [-Werror,-Wconstant-conversion]
for (i = ARRAY_SIZE(iwl_dev_info_table) - 1; i >= 0; i--) {
~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
This is still harmless, as the loop correctly terminates, but adding
an extra range check makes that obvious to both readers and to the
compiler.
Fixes: 3f7320428fa4 ("iwlwifi: pcie: simplify iwl_pci_find_dev_info()")
Reported-by: kernel test robot <redacted>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
Changes in v3:
- make it actually work with gcc-11
- fix commit message s/clang/gcc-11/
Changes in v2:
- replace int cast with a range check
---
drivers/net/wireless/intel/iwlwifi/pcie/drv.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
On Thu, Nov 18, 2021 at 03:21:02PM +0100, Arnd Bergmann wrote:
From: Arnd Bergmann <arnd@arndb.de>
gcc-11 points out a potential issue with integer overflow when
the iwl_dev_info_table[] array is empty:
drivers/net/wireless/intel/iwlwifi/pcie/drv.c:1344:42: error: implicit conversion from 'unsigned long' to 'int' changes value from 18446744073709551615 to -1 [-Werror,-Wconstant-conversion]
for (i = ARRAY_SIZE(iwl_dev_info_table) - 1; i >= 0; i--) {
~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
For what it's worth, I do see this warning with Clang when both
CONFIG_IWLDVM and CONFIG_IWLMVM are disabled and looking through the GCC
warning docs [1], I do not see a -Wconstant-conversion option? Maybe
there is another warning that is similar but that warning right there
appears to have come from clang, as it matches mine exactly.
drivers/net/wireless/intel/iwlwifi/pcie/drv.c:1344:42: error: implicit conversion from 'unsigned long' to 'int' changes value from 18446744073709551615 to -1 [-Werror,-Wconstant-conversion]
for (i = ARRAY_SIZE(iwl_dev_info_table) - 1; i >= 0; i--) {
~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
1 error generated.
[1]: https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html
This is still harmless, as the loop correctly terminates, but adding
an extra range check makes that obvious to both readers and to the
compiler.
Fixes: 3f7320428fa4 ("iwlwifi: pcie: simplify iwl_pci_find_dev_info()")
Reported-by: kernel test robot <redacted>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Regardless of above, this resolves the warning for clang.
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
quoted hunk
---
Changes in v3:
- make it actually work with gcc-11
- fix commit message s/clang/gcc-11/
Changes in v2:
- replace int cast with a range check
---
drivers/net/wireless/intel/iwlwifi/pcie/drv.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
On Thu, Nov 18, 2021 at 5:03 PM Nathan Chancellor [off-list ref] wrote:
On Thu, Nov 18, 2021 at 03:21:02PM +0100, Arnd Bergmann wrote:
quoted
From: Arnd Bergmann <arnd@arndb.de>
gcc-11 points out a potential issue with integer overflow when
the iwl_dev_info_table[] array is empty:
drivers/net/wireless/intel/iwlwifi/pcie/drv.c:1344:42: error: implicit conversion from 'unsigned long' to 'int' changes value from 18446744073709551615 to -1 [-Werror,-Wconstant-conversion]
for (i = ARRAY_SIZE(iwl_dev_info_table) - 1; i >= 0; i--) {
~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
For what it's worth, I do see this warning with Clang when both
CONFIG_IWLDVM and CONFIG_IWLMVM are disabled and looking through the GCC
warning docs [1], I do not see a -Wconstant-conversion option? Maybe
there is another warning that is similar but that warning right there
appears to have come from clang, as it matches mine exactly.
drivers/net/wireless/intel/iwlwifi/pcie/drv.c:1344:42: error: implicit conversion from 'unsigned long' to 'int' changes value from 18446744073709551615 to -1 [-Werror,-Wconstant-conversion]
for (i = ARRAY_SIZE(iwl_dev_info_table) - 1; i >= 0; i--) {
~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
1 error generated.
[1]: https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html
Ok, got it: it turns out this warning /also/ happens with gcc-11 and
the initial changelog was the one for matching the clang warning.
This is the gcc output, which is very similar but has a different
warning option.
drivers/net/wireless/intel/iwlwifi/pcie/drv.c: In function
'iwl_pci_find_dev_info':
include/linux/kernel.h:46:25: error: overflow in conversion from 'long
unsigned int' to 'int' changes value from '18446744073709551615' to
'-1' [-Werror=overflow]
46 | #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) +
__must_be_array(arr))
| ^
drivers/net/wireless/intel/iwlwifi/pcie/drv.c:1344:18: note: in
expansion of macro 'ARRAY_SIZE'
1344 | for (i = ARRAY_SIZE(iwl_dev_info_table) - 1; i >= 0; i--) {
My v2 patch only addressed the clang warning, while v3 works with both
gcc and clang. I can send a v4 if I should update the changelog again
to explain that, but I suppose it's still close enough.
Arnd
From: Kalle Valo <hidden> Date: 2021-11-22 18:35:43
Arnd Bergmann [off-list ref] wrote:
From: Arnd Bergmann <arnd@arndb.de>
Both gcc-11 and clang point out a potential issue with integer overflow when
the iwl_dev_info_table[] array is empty. This is what clang warns:
drivers/net/wireless/intel/iwlwifi/pcie/drv.c:1344:42: error: implicit conversion from 'unsigned long' to 'int' changes value from 18446744073709551615 to -1 [-Werror,-Wconstant-conversion]
for (i = ARRAY_SIZE(iwl_dev_info_table) - 1; i >= 0; i--) {
~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
This is still harmless, as the loop correctly terminates, but adding
an extra range check makes that obvious to both readers and to the
compiler.
Fixes: 3f7320428fa4 ("iwlwifi: pcie: simplify iwl_pci_find_dev_info()")
Reported-by: kernel test robot <redacted>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>