| Message ID | 20240822133908.1042240-2-lizetao1@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Some modifications to optimize code readability | expand |
* Li Zetao (lizetao1@huawei.com) wrote: > When copying data to user, it needs to determine the copy length. > It is easier to understand using min() here. > > Signed-off-by: Li Zetao <lizetao1@huawei.com> > --- > net/atm/addr.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/net/atm/addr.c b/net/atm/addr.c > index 0530b63f509a..6c4c942b2cb9 100644 > --- a/net/atm/addr.c > +++ b/net/atm/addr.c > @@ -136,7 +136,7 @@ int atm_get_addr(struct atm_dev *dev, struct sockaddr_atmsvc __user * buf, > unsigned long flags; > struct atm_dev_addr *this; > struct list_head *head; > - int total = 0, error; > + size_t total = 0, error; Aren't you accidentally changing the type of 'error' there, and the function returns 'int'. Dave > struct sockaddr_atmsvc *tmp_buf, *tmp_bufp; > > spin_lock_irqsave(&dev->lock, flags); > @@ -155,7 +155,7 @@ int atm_get_addr(struct atm_dev *dev, struct sockaddr_atmsvc __user * buf, > memcpy(tmp_bufp++, &this->addr, sizeof(struct sockaddr_atmsvc)); > spin_unlock_irqrestore(&dev->lock, flags); > error = total > size ? -E2BIG : total; > - if (copy_to_user(buf, tmp_buf, total < size ? total : size)) > + if (copy_to_user(buf, tmp_buf, min(total, size))) > error = -EFAULT; > kfree(tmp_buf); > return error; > -- > 2.34.1 >
Hi, 在 2024/8/22 21:39, Dr. David Alan Gilbert 写道: > * Li Zetao (lizetao1@huawei.com) wrote: >> When copying data to user, it needs to determine the copy length. >> It is easier to understand using min() here. >> >> Signed-off-by: Li Zetao <lizetao1@huawei.com> >> --- >> net/atm/addr.c | 4 ++-- >> 1 file changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/net/atm/addr.c b/net/atm/addr.c >> index 0530b63f509a..6c4c942b2cb9 100644 >> --- a/net/atm/addr.c >> +++ b/net/atm/addr.c >> @@ -136,7 +136,7 @@ int atm_get_addr(struct atm_dev *dev, struct sockaddr_atmsvc __user * buf, >> unsigned long flags; >> struct atm_dev_addr *this; >> struct list_head *head; >> - int total = 0, error; >> + size_t total = 0, error; > > Aren't you accidentally changing the type of 'error' there, and the function > returns 'int'. This is intentionally modified because the input parameter size is of type size_t. If total is of type int, the compiler will report an error when the min() is called. > > Dav > > >> struct sockaddr_atmsvc *tmp_buf, *tmp_bufp; >> >> spin_lock_irqsave(&dev->lock, flags); >> @@ -155,7 +155,7 @@ int atm_get_addr(struct atm_dev *dev, struct sockaddr_atmsvc __user * buf, >> memcpy(tmp_bufp++, &this->addr, sizeof(struct sockaddr_atmsvc)); >> spin_unlock_irqrestore(&dev->lock, flags); >> error = total > size ? -E2BIG : total; >> - if (copy_to_user(buf, tmp_buf, total < size ? total : size)) >> + if (copy_to_user(buf, tmp_buf, min(total, size))) >> error = -EFAULT; >> kfree(tmp_buf); >> return error; >> -- >> 2.34.1 >> Thanks, Li Zetao.
On 8/22/2024 6:50 AM, Li Zetao wrote: > Hi, > > 在 2024/8/22 21:39, Dr. David Alan Gilbert 写道: >> * Li Zetao (lizetao1@huawei.com) wrote: >>> When copying data to user, it needs to determine the copy length. >>> It is easier to understand using min() here. >>> >>> Signed-off-by: Li Zetao <lizetao1@huawei.com> >>> --- >>> net/atm/addr.c | 4 ++-- >>> 1 file changed, 2 insertions(+), 2 deletions(-) >>> >>> diff --git a/net/atm/addr.c b/net/atm/addr.c >>> index 0530b63f509a..6c4c942b2cb9 100644 >>> --- a/net/atm/addr.c >>> +++ b/net/atm/addr.c >>> @@ -136,7 +136,7 @@ int atm_get_addr(struct atm_dev *dev, struct sockaddr_atmsvc __user * buf, >>> unsigned long flags; >>> struct atm_dev_addr *this; >>> struct list_head *head; >>> - int total = 0, error; >>> + size_t total = 0, error; >> >> Aren't you accidentally changing the type of 'error' there, and the function >> returns 'int'. > This is intentionally modified because the input parameter size is of > type size_t. If total is of type int, the compiler will report an error > when the min() is called. >> Yea, but what you're missing is that error was an int before and is now a size_t which can't be negative. I think this either needs to be: size_t total = 0; int error or better yet.... >> Dav >> >> >>> struct sockaddr_atmsvc *tmp_buf, *tmp_bufp; >>> >>> spin_lock_irqsave(&dev->lock, flags); >>> @@ -155,7 +155,7 @@ int atm_get_addr(struct atm_dev *dev, struct sockaddr_atmsvc __user * buf, >>> memcpy(tmp_bufp++, &this->addr, sizeof(struct sockaddr_atmsvc)); >>> spin_unlock_irqrestore(&dev->lock, flags); >>> error = total > size ? -E2BIG : total; >>> - if (copy_to_user(buf, tmp_buf, total < size ? total : size)) >>> + if (copy_to_user(buf, tmp_buf, min(total, size))) >>> error = -EFAULT; Couldn't you just use min_t here instead of changing the variable sizes? Thanks, Jake
diff --git a/net/atm/addr.c b/net/atm/addr.c index 0530b63f509a..6c4c942b2cb9 100644 --- a/net/atm/addr.c +++ b/net/atm/addr.c @@ -136,7 +136,7 @@ int atm_get_addr(struct atm_dev *dev, struct sockaddr_atmsvc __user * buf, unsigned long flags; struct atm_dev_addr *this; struct list_head *head; - int total = 0, error; + size_t total = 0, error; struct sockaddr_atmsvc *tmp_buf, *tmp_bufp; spin_lock_irqsave(&dev->lock, flags); @@ -155,7 +155,7 @@ int atm_get_addr(struct atm_dev *dev, struct sockaddr_atmsvc __user * buf, memcpy(tmp_bufp++, &this->addr, sizeof(struct sockaddr_atmsvc)); spin_unlock_irqrestore(&dev->lock, flags); error = total > size ? -E2BIG : total; - if (copy_to_user(buf, tmp_buf, total < size ? total : size)) + if (copy_to_user(buf, tmp_buf, min(total, size))) error = -EFAULT; kfree(tmp_buf); return error;
When copying data to user, it needs to determine the copy length. It is easier to understand using min() here. Signed-off-by: Li Zetao <lizetao1@huawei.com> --- net/atm/addr.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)