Messages in this thread | | | Date | Wed, 21 Apr 2004 00:25:45 +0100 | From | viro@parcelfa ... | Subject | Re: [CHECKER] Security reports involving isspace() |
| |
On Tue, Apr 20, 2004 at 03:14:21PM -0700, ken@coverity.com wrote: > Here are some more static analysis reports from Coverity. These are > places where the kernel gets a scalar from the user and then uses it as an > array index with out bounds checking it. > > All of the reports below deal with the isspace macro. It expands to an > access to a static array with 256 entries. If we use an unsigned char to > index into the array, there are no problems. However, when that char is > signed, we can index off the left of the array. > > It seems like this isn't a big deal, but if the isspace array is located > after some important data structure, we could leak information.
#define __ismask(x) (_ctype[(int)(unsigned char)(x)]) #define isspace(c) ((__ismask(c)&(_S)) != 0)
Figuring out why the reports mentioned in the quoted text are bullshit is left as an exercise for readers. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |