On Thu 2013-08-22 19:01:46, Lee, Chun-Yi wrote: > Per PKCS1 spec, the EMSA-PKCS1-v1_5 encoded message is leading by 0x00 0x01 in > its first 2 bytes. The leading zero byte is suppressed by MPI so we pass a > pointer to the _preceding_ byte to RSA_verify() in original code, but it has > risk for the byte is not zero because it's not in EM buffer's scope, neither > RSA_verify() nor mpi_get_buffer() didn't take care the leading byte. > > To avoid the risk, that's better we explicitly add the leading zero byte to EM > for pass to RSA_verify(). This patch allocate a _EM buffer to capture the > result from RSA_I2OSP(), then set the first byte to zero in EM and copy the > remaining bytes from _EM. > > Reviewed-by: Jiri Kosina <jkosina@xxxxxxx> > Signed-off-by: Lee, Chun-Yi <jlee@xxxxxxxx> > - ret = RSA_verify(H, EM - 1, k, sig->digest_size, > + EM = kmalloc(k, GFP_KERNEL); > + memset(EM, 0, 1); > + memcpy(EM + 1, _EM, k-1); > + kfree(_EM); Spot a crash waiting to happen. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
