forwarded to devel@xxxxxxxxxx thanks, Len Brown, Intel Open Source Technology Center ---------- Forwarded message ---------- Date: Tue, 10 Nov 2009 11:02:49 +0200 (SAST) From: Dan Carpenter <error27@xxxxxxxxx> To: linux-acpi@xxxxxxxxxxxxxxx Cc: lenb@xxxxxxxxxx Subject: [patch] prevent possible NULL dereference. Move the check for walk_state->thread before the dereference. Found by smatch static checker. Compile tested. regards, dan carpenter Signed-off-by: Dan Carpenter <error27@xxxxxxxxx> --- orig/drivers/acpi/acpica/exmutex.c 2009-11-07 09:46:53.000000000 +0200 +++ devel/drivers/acpi/acpica/exmutex.c 2009-11-07 09:48:16.000000000 +0200 @@ -375,6 +375,15 @@ return_ACPI_STATUS(AE_AML_MUTEX_NOT_ACQUIRED); } + /* Must have a valid thread ID */ + + if (!walk_state->thread) { + ACPI_ERROR((AE_INFO, + "Cannot release Mutex [%4.4s], null thread info", + acpi_ut_get_node_name(obj_desc->mutex.node))); + return_ACPI_STATUS(AE_AML_INTERNAL); + } + /* * The Mutex is owned, but this thread must be the owner. * Special case for Global Lock, any thread can release @@ -392,15 +401,6 @@ return_ACPI_STATUS(AE_AML_NOT_OWNER); } - /* Must have a valid thread ID */ - - if (!walk_state->thread) { - ACPI_ERROR((AE_INFO, - "Cannot release Mutex [%4.4s], null thread info", - acpi_ut_get_node_name(obj_desc->mutex.node))); - return_ACPI_STATUS(AE_AML_INTERNAL); - } - /* * The sync level of the mutex must be equal to the current sync level. In * other words, the current level means that at least one mutex at that -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html