| Message ID | 20230610204044.3653-4-demi@invisiblethingslab.com |
|---|---|
| State | New |
| Headers | show |
| Series | Make sscanf() stricter | expand |
From: Rasmus Villemoes > Sent: 12 June 2023 12:08 > > On 10/06/2023 22.40, Demi Marie Obenour wrote: > > Passing spaces before e.g. an integer is usually > > not intended. > > Maybe, maybe not. But it's mandated by POSIX/C99. > > And of course we are free to ignore that and implement our own semantics > (though within the constraints that we really want -Wformat to help us), > but there seems to be existing code in-tree that relies on this > behavior. For example I think this will break > fsl_sata_intr_coalescing_store() which uses a scanf format of "%u%u". > > Sure, that could just say "%u %u" instead, but the point is that > currently it doesn't. So without some reasonably thorough analysis > across the tree, and updates of affected callers, NAK. It would almost certainly need to be " %u %u" to allow for userspace generating the input with "%6u %6u", David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
diff --git a/lib/vsprintf.c b/lib/vsprintf.c index 9e53355c35b1d6260631868228ede1d178fe3325..665f6197f8313d653f67d7886b12c43942e058dd 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -3551,8 +3551,6 @@ int vsscanf(const char *buf, const char *fmt, va_list args) char *s = (char *)va_arg(args, char *); if (field_width == -1) field_width = SHRT_MAX; - /* first, skip leading white space in buffer */ - str = skip_spaces(str); /* now copy until next white space */ while (*str && !isspace(*str) && field_width--) @@ -3639,11 +3637,7 @@ int vsscanf(const char *buf, const char *fmt, va_list args) return num; } - /* have some sort of integer conversion. - * first, skip white space in buffer. - */ - str = skip_spaces(str); - + /* have some sort of integer conversion. */ digit = *str; if (is_sign && digit == '-') { if (field_width == 1)
Passing spaces before e.g. an integer is usually not intended. This was suggested by Christoph in https://lore.kernel.org/lkml/ZIQrohcizoj4bZWx@infradead.org/. Suggested-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Demi Marie Obenour <demi@invisiblethingslab.com> --- lib/vsprintf.c | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-)