Top posting and just adding a few interested parties ...
On 12/4/23 13:00, Prarit Bhargava wrote:
The gcc plugin -fanalyzer [1] tries to detect various
patterns of incorrect behaviour. The tool reports
drivers/acpi/acpi_extlog.c: In function ‘extlog_exit’:
drivers/acpi/acpi_extlog.c:307:12: warning: check of ‘extlog_l1_addr’ for NULL after already dereferencing it [-Wanalyzer-deref-before-check]
|
| 306 | ((struct extlog_l1_head *)extlog_l1_addr)->flags &= ~FLAG_OS_OPTIN;
| | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~
| | |
| | (1) pointer ‘extlog_l1_addr’ is dereferenced here
| 307 | if (extlog_l1_addr)
| | ~
| | |
| | (2) pointer ‘extlog_l1_addr’ is checked for NULL here but it was already dereferenced at (1)
|
Fix the null dereference check in extlog_exit().
[1] https://gcc.gnu.org/onlinedocs/gcc-10.1.0/gcc/Static-Analyzer-Options.html
CC: "Rafael J. Wysocki" <rafael@xxxxxxxxxx>
CC: Len Brown <lenb@xxxxxxxxxx>
CC: linux-acpi@xxxxxxxxxxxxxxx
Signed-off-by: Prarit Bhargava <prarit@xxxxxxxxxx>
---
drivers/acpi/acpi_extlog.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/drivers/acpi/acpi_extlog.c b/drivers/acpi/acpi_extlog.c
index e120a96e1eae..193147769146 100644
--- a/drivers/acpi/acpi_extlog.c
+++ b/drivers/acpi/acpi_extlog.c
@@ -303,9 +303,10 @@ static int __init extlog_init(void)
static void __exit extlog_exit(void)
{
mce_unregister_decode_chain(&extlog_mce_dec);
- ((struct extlog_l1_head *)extlog_l1_addr)->flags &= ~FLAG_OS_OPTIN;
- if (extlog_l1_addr)
+ if (extlog_l1_addr) {
+ ((struct extlog_l1_head *)extlog_l1_addr)->flags &= ~FLAG_OS_OPTIN;
acpi_os_unmap_iomem(extlog_l1_addr, l1_size);
+ }
if (elog_addr)
acpi_os_unmap_iomem(elog_addr, elog_size);
release_mem_region(elog_base, elog_size);
