On Mon, Dec 4, 2023 at 7:00 PM Prarit Bhargava <prarit@xxxxxxxxxx> 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); > -- Applied as 6.8 material with minor edits in the subject and changelog, thanks!
