On 04/15/2017 06:12 PM, Tom Rini wrote:
> On Sat, Apr 15, 2017 at 03:58:55PM +0200, Heinrich Schuchardt wrote:
>
>> If bootargs is not assigned getenv("bootargs") will
>> return NULL.
>> Some part of the code is checking for this condition.
>> Other parts dereference a possible NULL pointer.
>>
>> The problem was indicated by cppcheck.
>>
>> Signed-off-by: Heinrich Schuchardt <[email protected]>
>> ---
>> arch/x86/lib/zimage.c | 9 +++++----
>> 1 file changed, 5 insertions(+), 4 deletions(-)
>>
>> diff --git a/arch/x86/lib/zimage.c b/arch/x86/lib/zimage.c
>> index aafbeb01f9..9b564340a6 100644
>> --- a/arch/x86/lib/zimage.c
>> +++ b/arch/x86/lib/zimage.c
>> @@ -48,12 +48,14 @@ static void build_command_line(char *command_line, int
>> auto_boot)
>>
>> command_line[0] = '\0';
>>
>> - env_command_line = getenv("bootargs");
>> + env_command_line = getenv("bootargs");
>> +
>> + if (!env_command_line)
>> + env_command_line = "";
>>
>> /* set console= argument if we use a serial console */
>> if (!strstr(env_command_line, "console=")) {
>> if (!strcmp(getenv("stdout"), "serial")) {
>> -
>> /* We seem to use serial console */
>> sprintf(command_line, "console=ttyS0,%s ",
>> getenv("baudrate"));
>> @@ -63,8 +65,7 @@ static void build_command_line(char *command_line, int
>> auto_boot)
>> if (auto_boot)
>> strcat(command_line, "auto ");
>>
>> - if (env_command_line)
>> - strcat(command_line, env_command_line);
>> + strcat(command_line, env_command_line);
>>
>> printf("Kernel command line: \"%s\"\n", command_line);
>> }
>
> I think this is a false positive from cppcheck. With env_command_line
> set to NULL, strstr will return NULL. The only other place we use
> env_command_line is further on where we alrady have a check. Thanks!
> Please, have a look at lib/string.c: strstr(NULL, b) will happily start searching at 0x0. So the result will depend on the memory content there. Should the first bytes be "foo, console=bar\0" the address of "console=" will be returned. Or maybe a security controller will stop the process due to illegal memory access. Best regards Heinrich Schuchardt
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