x86/MCE: Fix stack out-of-bounds write in mce-inject.c: Flags_read()

Each of the strings that we want to put into the buf[MAX_FLAG_OPT_SIZE]
in flags_read() is two characters long. But the sprintf() adds
a trailing newline and will add a terminating NUL byte. So
MAX_FLAG_OPT_SIZE needs to be 4.

sprintf() calls vsnprintf() and *that* does return:

" * The return value is the number of characters which would
 * be generated for the given input, excluding the trailing
 * '\0', as per ISO C99."

Note the "excluding".

Reported-by: Dmitry Vyukov <[email protected]>
Signed-off-by: Tony Luck <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Cc: [email protected]
Cc: linux-edac <[email protected]>
Link: http://lkml.kernel.org/r/20180427163707.ktaiysvbk3yhk4wm@agluck-desk

0 files changed, 0 insertions, 0 deletions