On Fri, Apr 18, 2008 at 09:08:55PM +0200, Julia Lawall wrote: > I found 63 occurrences of this problem with the following semantic match > (http://www.emn.fr/x-info/coccinelle/): > > @@ unsigned int i; @@ > > * i < 0 > > I looked through all of the results by hand, and they all seem to be > problems. In many cases, it seems like the variable should not be > unsigned as it is used to hold the return value of a function that might > return a negative error code, but I haven't looked into this in detail. > diff -u -p a/drivers/ieee1394/dv1394.c b/drivers/ieee1394/dv1394.c > *** a/drivers/ieee1394/dv1394.c 2008-03-12 14:13:13.000000000 +0100 > @@ -918,7 +918,7 @@ static int do_dv1394_init(struct video_c > /* default SYT offset is 3 cycles */ > init->syt_offset = 3; > > * if ( (init->channel > 63) || (init->channel < 0) ) > init->channel = 63; > > chan_mask = (u64)1 << init->channel; > diff -u -p a/drivers/ieee1394/video1394.c b/drivers/ieee1394/video1394.c > *** a/drivers/ieee1394/video1394.c 2008-03-12 14:13:13.000000000 +0100 > @@ -893,7 +893,7 @@ static long video1394_ioctl(struct file > if (unlikely(d == NULL)) > return -EFAULT; > > * if (unlikely((v.buffer<0) || (v.buffer>=d->num_desc - 1))) { > PRINT(KERN_ERR, ohci->host->id, > "Buffer %d out of range",v.buffer); > return -EINVAL; > @@ -959,7 +959,7 @@ static long video1394_ioctl(struct file > if (unlikely(d == NULL)) > return -EFAULT; > > * if (unlikely((v.buffer<0) || (v.buffer>d->num_desc - 1))) { > PRINT(KERN_ERR, ohci->host->id, > "Buffer %d out of range",v.buffer); > return -EINVAL; > @@ -1030,7 +1030,7 @@ static long video1394_ioctl(struct file > d = find_ctx(&ctx->context_list, OHCI_ISO_TRANSMIT, v.channel); > if (d == NULL) return -EFAULT; > > * if ((v.buffer<0) || (v.buffer>=d->num_desc - 1)) { > PRINT(KERN_ERR, ohci->host->id, > "Buffer %d out of range",v.buffer); > return -EINVAL; > @@ -1137,7 +1137,7 @@ static long video1394_ioctl(struct file > d = find_ctx(&ctx->context_list, OHCI_ISO_TRANSMIT, v.channel); > if (d == NULL) return -EFAULT; > > * if ((v.buffer<0) || (v.buffer>=d->num_desc-1)) { > PRINT(KERN_ERR, ohci->host->id, > "Buffer %d out of range",v.buffer); > return -EINVAL; I believe all these are essentially harmless. Due to the wrapping nature of unsigned arithmetic, while the first condition (x < 0) is always false, the condition it's attempting to catch will be caught by the second condition. We should probably remove the tests for < 0. -- Intel are signing my paycheques ... these opinions are still mine "Bill, look, we understand that you're interested in selling us this operating system, but compare it to ours. We can't possibly take such a retrograde step." -- To unsubscribe from this list: send the line "unsubscribe kernel-janitors" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
