2021-03-01 06:37:32

by 王擎

Subject: [PATCH] arch: mips: sibyte: Return -EFAULT if copy_to_user() fails

The copy_to_user() function returns the number of bytes remaining to be
copied, but we want to return -EFAULT if the copy doesn't complete.

Signed-off-by: Wang Qing <[email protected]>
---
arch/mips/sibyte/common/sb_tbprof.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/mips/sibyte/common/sb_tbprof.c b/arch/mips/sibyte/common/sb_tbprof.c
index f80d7a7..eac125f
--- a/arch/mips/sibyte/common/sb_tbprof.c
+++ b/arch/mips/sibyte/common/sb_tbprof.c
@@ -465,7 +465,7 @@ static ssize_t sbprof_tb_read(struct file *filp, char *buf,
if (err) {
*offp = cur_off + cur_count - err;
mutex_unlock(&sbp.lock);
- return err;
+ return -EFAULT;
}
pr_debug(DEVNAME ": read from sample %d, %d bytes\n",
cur_sample, cur_count);
--
2.7.4

2021-03-01 08:58:09

by Sergei Shtylyov

Subject: Re: [PATCH] arch: mips: sibyte: Return -EFAULT if copy_to_user() fails

Hello!

On 01.03.2021 9:33, Wang Qing wrote:

> The copy_to_user() function returns the number of bytes remaining to be
> copied, but we want to return -EFAULT if the copy doesn't complete.

Then 'err' is hardly a good name for that variable. :-)

>
> Signed-off-by: Wang Qing <[email protected]>
> ---
> arch/mips/sibyte/common/sb_tbprof.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/mips/sibyte/common/sb_tbprof.c b/arch/mips/sibyte/common/sb_tbprof.c
> index f80d7a7..eac125f
> --- a/arch/mips/sibyte/common/sb_tbprof.c
> +++ b/arch/mips/sibyte/common/sb_tbprof.c
> @@ -465,7 +465,7 @@ static ssize_t sbprof_tb_read(struct file *filp, char *buf,
> if (err) {
> *offp = cur_off + cur_count - err;
> mutex_unlock(&sbp.lock);
> - return err;
> + return -EFAULT;
> }
> pr_debug(DEVNAME ": read from sample %d, %d bytes\n",
> cur_sample, cur_count);

MBR, Sergei

2021-03-04 05:27:50

by Maciej W. Rozycki

Subject: Re: [PATCH] arch: mips: sibyte: Return -EFAULT if copy_to_user() fails

On Mon, 1 Mar 2021, Sergei Shtylyov wrote:

> > The copy_to_user() function returns the number of bytes remaining to be
> > copied, but we want to return -EFAULT if the copy doesn't complete.
>
> Then 'err' is hardly a good name for that variable. :-)

Something like `left' might be better, especially as it's the sole use.
Also it's been like this from the beginning, so:

Fixes: bb9b813bb665 ("[MIPS] Sibyte: Fix ZBbus profiler")

or maybe:

Fixes: d619f38fdacb ("[MIPS] Add bcm1480 ZBus trace support, fix wait related bugs")

(since the file was renamed from a different name with the latter commit)
would I think be helpful for backports too. It looks like potentially
quite a nasty bug to me if someone actually uses this piece (I haven't).

Maciej