6.6-stable review patch. If anyone has any objections, please let me know.
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From: Prarit Bhargava prarit@redhat.com
[ Upstream commit 72d9b9747e78979510e9aafdd32eb99c7aa30dd1 ]
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 pointer dereference check in extlog_exit().
Link: https://gcc.gnu.org/onlinedocs/gcc-10.1.0/gcc/Static-Analyzer-Options.html # [1]
Signed-off-by: Prarit Bhargava prarit@redhat.com Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- 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 71e8d4e7a36c..ca87a0939135 100644 --- a/drivers/acpi/acpi_extlog.c +++ b/drivers/acpi/acpi_extlog.c @@ -308,9 +308,10 @@ 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);