* [PATCH] Staging: rtl8712: Use mem_dup() instead of copy_from_user() @ 2015-03-22 19:04 Cristina Opriceana 2015-03-22 20:04 ` [Outreachy kernel] " Julia Lawall 0 siblings, 1 reply; 4+ messages in thread From: Cristina Opriceana @ 2015-03-22 19:04 UTC (permalink / raw) To: outreachy-kernel; +Cc: outreachy-kernel Use mem_dup() instead of its duplicated implementation in order to simplify code. Found with coccinelle. Signed-off-by: Cristina Opriceana <cristina.opriceana@gmail.com> --- drivers/staging/rtl8712/rtl871x_ioctl_linux.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-) diff --git a/drivers/staging/rtl8712/rtl871x_ioctl_linux.c b/drivers/staging/rtl8712/rtl871x_ioctl_linux.c index 81f39c3..c39d031 100644 --- a/drivers/staging/rtl8712/rtl871x_ioctl_linux.c +++ b/drivers/staging/rtl8712/rtl871x_ioctl_linux.c @@ -1912,13 +1912,9 @@ static int r871x_mp_ioctl_hdl(struct net_device *dev, bset = (u8)(p->flags & 0xFFFF); len = p->length; pparmbuf = NULL; - pparmbuf = kmalloc(len, GFP_ATOMIC); - if (pparmbuf == NULL) { - ret = -ENOMEM; - goto _r871x_mp_ioctl_hdl_exit; - } - if (copy_from_user(pparmbuf, p->pointer, len)) { - ret = -EFAULT; + pparmbuf = memdup_user(p->pointer, len); + if (IS_ERR(pparmbuf)) { + ret = PTR_ERR(pparmbuf); goto _r871x_mp_ioctl_hdl_exit; } poidparam = (struct mp_ioctl_param *)pparmbuf; -- 1.9.1 ^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [Outreachy kernel] [PATCH] Staging: rtl8712: Use mem_dup() instead of copy_from_user() 2015-03-22 19:04 [PATCH] Staging: rtl8712: Use mem_dup() instead of copy_from_user() Cristina Opriceana @ 2015-03-22 20:04 ` Julia Lawall 2015-03-23 11:24 ` Cristina Opriceana 0 siblings, 1 reply; 4+ messages in thread From: Julia Lawall @ 2015-03-22 20:04 UTC (permalink / raw) To: Cristina Opriceana; +Cc: outreachy-kernel On Sun, 22 Mar 2015, Cristina Opriceana wrote: > Use mem_dup() instead of its duplicated implementation in order > to simplify code. Found with coccinelle. > > Signed-off-by: Cristina Opriceana <cristina.opriceana@gmail.com> > --- > drivers/staging/rtl8712/rtl871x_ioctl_linux.c | 10 +++------- > 1 file changed, 3 insertions(+), 7 deletions(-) > > diff --git a/drivers/staging/rtl8712/rtl871x_ioctl_linux.c b/drivers/staging/rtl8712/rtl871x_ioctl_linux.c > index 81f39c3..c39d031 100644 > --- a/drivers/staging/rtl8712/rtl871x_ioctl_linux.c > +++ b/drivers/staging/rtl8712/rtl871x_ioctl_linux.c > @@ -1912,13 +1912,9 @@ static int r871x_mp_ioctl_hdl(struct net_device *dev, > bset = (u8)(p->flags & 0xFFFF); > len = p->length; > pparmbuf = NULL; > - pparmbuf = kmalloc(len, GFP_ATOMIC); > - if (pparmbuf == NULL) { > - ret = -ENOMEM; > - goto _r871x_mp_ioctl_hdl_exit; > - } > - if (copy_from_user(pparmbuf, p->pointer, len)) { > - ret = -EFAULT; > + pparmbuf = memdup_user(p->pointer, len); There is a potential problem with this. memdup_user uses GFP_KERNEL (blocking allowed), while the original code used GFP_ATOMIC (blocking not allowed). You could check whether any locks can be held on the way to this code, which would require GFP_ATOMIC. On the other hand, it may be that copy_from_user can only be used when blocking is allowed. julia > + if (IS_ERR(pparmbuf)) { > + ret = PTR_ERR(pparmbuf); > goto _r871x_mp_ioctl_hdl_exit; > } > poidparam = (struct mp_ioctl_param *)pparmbuf; > -- > 1.9.1 > > -- > You received this message because you are subscribed to the Google Groups "outreachy-kernel" group. > To unsubscribe from this group and stop receiving emails from it, send an email to outreachy-kernel+unsubscribe@googlegroups.com. > To post to this group, send email to outreachy-kernel@googlegroups.com. > To view this discussion on the web visit https://groups.google.com/d/msgid/outreachy-kernel/20150322190400.GA1115%40Inspiron. > For more options, visit https://groups.google.com/d/optout. > ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [Outreachy kernel] [PATCH] Staging: rtl8712: Use mem_dup() instead of copy_from_user() 2015-03-22 20:04 ` [Outreachy kernel] " Julia Lawall @ 2015-03-23 11:24 ` Cristina Opriceana 2015-03-23 13:53 ` Julia Lawall 0 siblings, 1 reply; 4+ messages in thread From: Cristina Opriceana @ 2015-03-23 11:24 UTC (permalink / raw) To: Julia Lawall; +Cc: outreachy-kernel On Du, 2015-03-22 at 21:04 +0100, Julia Lawall wrote: > > On Sun, 22 Mar 2015, Cristina Opriceana wrote: > > > Use mem_dup() instead of its duplicated implementation in order > > to simplify code. Found with coccinelle. > > > > Signed-off-by: Cristina Opriceana <cristina.opriceana@gmail.com> > > --- > > drivers/staging/rtl8712/rtl871x_ioctl_linux.c | 10 +++------- > > 1 file changed, 3 insertions(+), 7 deletions(-) > > > > diff --git a/drivers/staging/rtl8712/rtl871x_ioctl_linux.c b/drivers/staging/rtl8712/rtl871x_ioctl_linux.c > > index 81f39c3..c39d031 100644 > > --- a/drivers/staging/rtl8712/rtl871x_ioctl_linux.c > > +++ b/drivers/staging/rtl8712/rtl871x_ioctl_linux.c > > @@ -1912,13 +1912,9 @@ static int r871x_mp_ioctl_hdl(struct net_device *dev, > > bset = (u8)(p->flags & 0xFFFF); > > len = p->length; > > pparmbuf = NULL; > > - pparmbuf = kmalloc(len, GFP_ATOMIC); > > - if (pparmbuf == NULL) { > > - ret = -ENOMEM; > > - goto _r871x_mp_ioctl_hdl_exit; > > - } > > - if (copy_from_user(pparmbuf, p->pointer, len)) { > > - ret = -EFAULT; > > + pparmbuf = memdup_user(p->pointer, len); > > There is a potential problem with this. memdup_user uses GFP_KERNEL > (blocking allowed), while the original code used GFP_ATOMIC (blocking not > allowed). You could check whether any locks can be held on the way to > this code, which would require GFP_ATOMIC. On the other hand, it may be > that copy_from_user can only be used when blocking is allowed. > > julia > As far as i understand, since copy_from_user() may sleep, it cannot be used while holding a lock. So, the use of GFP_ATOMIC might be useless in this context. Either that or copy_from_user shouldn't be used, which is not the case because the purpose of this function is to receive a command from the userspace and call its associated handler. Cristina ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [Outreachy kernel] [PATCH] Staging: rtl8712: Use mem_dup() instead of copy_from_user() 2015-03-23 11:24 ` Cristina Opriceana @ 2015-03-23 13:53 ` Julia Lawall 0 siblings, 0 replies; 4+ messages in thread From: Julia Lawall @ 2015-03-23 13:53 UTC (permalink / raw) To: Cristina Opriceana; +Cc: outreachy-kernel On Mon, 23 Mar 2015, Cristina Opriceana wrote: > On Du, 2015-03-22 at 21:04 +0100, Julia Lawall wrote: > > > > On Sun, 22 Mar 2015, Cristina Opriceana wrote: > > > > > Use mem_dup() instead of its duplicated implementation in order > > > to simplify code. Found with coccinelle. > > > > > > Signed-off-by: Cristina Opriceana <cristina.opriceana@gmail.com> > > > --- > > > drivers/staging/rtl8712/rtl871x_ioctl_linux.c | 10 +++------- > > > 1 file changed, 3 insertions(+), 7 deletions(-) > > > > > > diff --git a/drivers/staging/rtl8712/rtl871x_ioctl_linux.c b/drivers/staging/rtl8712/rtl871x_ioctl_linux.c > > > index 81f39c3..c39d031 100644 > > > --- a/drivers/staging/rtl8712/rtl871x_ioctl_linux.c > > > +++ b/drivers/staging/rtl8712/rtl871x_ioctl_linux.c > > > @@ -1912,13 +1912,9 @@ static int r871x_mp_ioctl_hdl(struct net_device *dev, > > > bset = (u8)(p->flags & 0xFFFF); > > > len = p->length; > > > pparmbuf = NULL; > > > - pparmbuf = kmalloc(len, GFP_ATOMIC); > > > - if (pparmbuf == NULL) { > > > - ret = -ENOMEM; > > > - goto _r871x_mp_ioctl_hdl_exit; > > > - } > > > - if (copy_from_user(pparmbuf, p->pointer, len)) { > > > - ret = -EFAULT; > > > + pparmbuf = memdup_user(p->pointer, len); > > > > There is a potential problem with this. memdup_user uses GFP_KERNEL > > (blocking allowed), while the original code used GFP_ATOMIC (blocking not > > allowed). You could check whether any locks can be held on the way to > > this code, which would require GFP_ATOMIC. On the other hand, it may be > > that copy_from_user can only be used when blocking is allowed. > > > > julia > > > As far as i understand, since copy_from_user() may sleep, it cannot be > used while holding a lock. So, the use of GFP_ATOMIC might be useless in > this context. > Either that or copy_from_user shouldn't be used, which is not the case > because the purpose of this function is to receive a command from the > userspace and call its associated handler. OK, it would be good to add a note about this to the commit message. julia ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2015-03-23 13:53 UTC | newest] Thread overview: 4+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2015-03-22 19:04 [PATCH] Staging: rtl8712: Use mem_dup() instead of copy_from_user() Cristina Opriceana 2015-03-22 20:04 ` [Outreachy kernel] " Julia Lawall 2015-03-23 11:24 ` Cristina Opriceana 2015-03-23 13:53 ` Julia Lawall
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