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| author | Arnd Bergmann <arnd@arndb.de> | 2016-11-10 19:44:46 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-11-11 19:45:08 +0300 |
| commit | 3a6d867612dce2035ca50cb02e7871d27c86aa72 (patch) | |
| tree | 6babb572b78290f960434e47b6341ccec30dc05a | |
| parent | e84efa32b9d2763fb92e73c8942100d8f55ad4ed (diff) | |
| download | linux-3a6d867612dce2035ca50cb02e7871d27c86aa72.tar.xz | |
x86: apm: avoid uninitialized data
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 <arnd@arndb.de>
Reviewed-by: Jiri Kosina <jkosina@suse.cz>
Reviewed-by: Luis R. Rodriguez <mcgrof@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | arch/x86/kernel/apm_32.c | 5 |
1 files changed, 4 insertions, 1 deletions
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) { |