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Subject[PATCH] ACPI / extlog: don't dereference extlog_l1_addr if it is null
Date
From: Colin Ian King <colin.king@canonical.com>

There is a check to see if extlog_l1_addr is null before calling
acpi_os_unmap_iomem, however, before that call there is a
dereference on this that could trip an oops. Move the
extlog_l1_addr dereference so it occurs only if it is not null.

Found by static analysis by smatch.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
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 b3842ff..183b7b2 100644
--- a/drivers/acpi/acpi_extlog.c
+++ b/drivers/acpi/acpi_extlog.c
@@ -309,9 +309,10 @@ static void __exit extlog_exit(void)
{
set_edac_report_status(old_edac_report_status);
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);
--
2.6.2


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