From 3a6d867612dce2035ca50cb02e7871d27c86aa72 Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Thu, 10 Nov 2016 17:44:46 +0100 Subject: x86: apm: avoid uninitialized data MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit apm_bios_call() can fail, and return a status in its argument structure. If that status however is zero during a call from apm_get_power_status(), we end up using data that may have never been set, as reported by "gcc -Wmaybe-uninitialized": arch/x86/kernel/apm_32.c: In function ‘apm’: arch/x86/kernel/apm_32.c:1729:17: error: ‘bx’ may be used uninitialized in this function [-Werror=maybe-uninitialized] arch/x86/kernel/apm_32.c:1835:5: error: ‘cx’ may be used uninitialized in this function [-Werror=maybe-uninitialized] arch/x86/kernel/apm_32.c:1730:17: note: ‘cx’ was declared here arch/x86/kernel/apm_32.c:1842:27: error: ‘dx’ may be used uninitialized in this function [-Werror=maybe-uninitialized] arch/x86/kernel/apm_32.c:1731:17: note: ‘dx’ was declared here This changes the function to return "APM_NO_ERROR" here, which makes the code more robust to broken BIOS versions, and avoids the warning. Signed-off-by: Arnd Bergmann Reviewed-by: Jiri Kosina Reviewed-by: Luis R. Rodriguez Signed-off-by: Linus Torvalds --- arch/x86/kernel/apm_32.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'arch/x86') diff --git a/arch/x86/kernel/apm_32.c b/arch/x86/kernel/apm_32.c index c7364bd633e1..51287cd90bf6 100644 --- a/arch/x86/kernel/apm_32.c +++ b/arch/x86/kernel/apm_32.c @@ -1042,8 +1042,11 @@ static int apm_get_power_status(u_short *status, u_short *bat, u_short *life) if (apm_info.get_power_status_broken) return APM_32_UNSUPPORTED; - if (apm_bios_call(&call)) + if (apm_bios_call(&call)) { + if (!call.err) + return APM_NO_ERROR; return call.err; + } *status = call.ebx; *bat = call.ecx; if (apm_info.get_power_status_swabinminutes) { -- cgit v1.2.3