Messages in this thread | | | Subject | Re: [PATCH] tty: nozomi: avoid sprintf buffer overflow | From | Jiri Slaby <> | Date | Tue, 29 Nov 2016 08:14:32 +0100 |
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On 11/28/2016, 10:04 PM, Arnd Bergmann wrote: > Testing with a gcc-7 snapshot produced an internal compiler error > for this file: > > drivers/tty/nozomi.c: In function 'receive_flow_control': > drivers/tty/nozomi.c:919:12: internal compiler error: in get_substring_ranges_for_loc, at input.c:1388 > static int receive_flow_control(struct nozomi *dc) > > I've reported this at https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78569 > but also noticed that the code line contains a stack overflow, as it prints > a string into a slightly shorter fixed-length 'tmp' variable. > > I don't see any point in the temporary variable, we can simply use > pr_debug() to print the output directly. This change should not change > any of the output but avoids both the stack overflow and the gcc > crash. > > The stack overflow will not happen unless a module load parameter is > also set to enable the debug messages. > > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > --- > drivers/tty/nozomi.c | 9 ++------- > 1 file changed, 2 insertions(+), 7 deletions(-) > > diff --git a/drivers/tty/nozomi.c b/drivers/tty/nozomi.c > index e2020a691058..17a182b28d52 100644 > --- a/drivers/tty/nozomi.c > +++ b/drivers/tty/nozomi.c > @@ -69,13 +69,8 @@ > #define NOZOMI_DEBUG_LEVEL 0x00 > > #define P_BUF_SIZE 128 > -#define NFO(_err_flag_, args...) \ > -do { \ > - char tmp[P_BUF_SIZE]; \ > - snprintf(tmp, sizeof(tmp), ##args); \ > - printk(_err_flag_ "[%d] %s(): %s\n", __LINE__, \ > - __func__, tmp); \ > -} while (0) > +#define NFO(_err_flag_, fmt, args...) \ > + pr_debug("[%d] %s(): " fmt "\n", __LINE__, __func__, ##args);
Could you also kill the now unused _err_flag_ parameter (including the only user of NFO)?
(Or inline pr_debug directly into the only user and kill NFO completely?)
thanks, -- js suse labs
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