[PATCH] soc: aspeed: fix a ternary sign expansion bug
viro at zeniv.linux.org.uk
Thu Apr 22 19:24:59 AEST 2021
On Thu, Apr 22, 2021 at 12:11:44PM +0300, Dan Carpenter wrote:
> The intent here was to return negative error codes but it actually
> returns positive values. The problem is that type promotion with
> ternary operations is quite complicated.
> "ret" is an int. "copied" is a u32. And the snoop_file_read() function
> returns long. What happens is that "ret" is cast to u32 and becomes
> positive then it's cast to long and it's still positive.
> Fix this by removing the ternary so that "ret" is type promoted directly
> to long.
Hmm... Let's grep for kfifo_to_user() - smells like a possible recurring bug...
samples/kfifo/bytestream-example.c:138: ret = kfifo_to_user(&test, buf, count, &copied);
samples/kfifo/inttype-example.c:131: ret = kfifo_to_user(&test, buf, count, &copied);
samples/kfifo/record-example.c:145: ret = kfifo_to_user(&test, buf, count, &copied);
All three are exactly like that one.
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