Roel Kluin writes: > According to http://cwe.mitre.org/data/slices/2000.html#14 due to optimization > A call to memset() can be removed as a dead store when the buffer is not used > after its value is overwritten. Does this optimization also occur during > compilation of the Linux kernel? Then I think I may have found some > vulnerabilities. One is sha1_update() where memset(temp, 0, sizeof(temp)); may > be removed. Any such dead store removal is up to the compiler and the lifetime of the object being clobbered. For 'auto' objects the optimization is certainly likely. This is only a problem if the memory (a thread stack, say) is recycled and leaked uninitialized to user-space, but such bugs are squashed fairly quickly upon discovery. (checking gcc-4.4.3) It seems that memset((volatile void*)&some_local_var, 0, sizeof(...)) just provokes a warning about the invalid type of memset()'s first parameter, but then still optimizes the operation away. You might need to call an out-of-line helper function for this to work. -- To unsubscribe from this list: send the line "unsubscribe linux-crypto" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
