| Message ID | 20180313205856.3309750-1-arnd@arndb.de |
|---|---|
| State | Accepted |
| Commit | a870a02cc963de35452bbed932560ed69725c4f2 |
| Headers | show |
| Series | pktgen: use dynamic allocation for debug print buffer | expand |
From: Arnd Bergmann <arnd@arndb.de> Date: Tue, 13 Mar 2018 21:58:39 +0100 > After the removal of the VLA, we get a harmless warning about a large > stack frame: > > net/core/pktgen.c: In function 'pktgen_if_write': > net/core/pktgen.c:1710:1: error: the frame size of 1076 bytes is larger than 1024 bytes [-Werror=frame-larger-than=] > > The function was previously shown to be safe despite hitting > the 1024 bye warning level. To get rid of the annoyging warning, > while keeping it readable, this changes it to use strndup_user(). > > Obviously this is not a fast path, so the kmalloc() overhead > can be disregarded. > > Fixes: 35951393bbff ("pktgen: Remove VLA usage") > Signed-off-by: Arnd Bergmann <arnd@arndb.de> Applied, thanks.
>> + kfree(buf); free tb? buf is an array. On Wed, Mar 14, 2018 at 8:25 AM, David Miller <davem@davemloft.net> wrote: > From: Arnd Bergmann <arnd@arndb.de> > Date: Tue, 13 Mar 2018 21:58:39 +0100 > >> After the removal of the VLA, we get a harmless warning about a large >> stack frame: >> >> net/core/pktgen.c: In function 'pktgen_if_write': >> net/core/pktgen.c:1710:1: error: the frame size of 1076 bytes is larger than 1024 bytes [-Werror=frame-larger-than=] >> >> The function was previously shown to be safe despite hitting >> the 1024 bye warning level. To get rid of the annoyging warning, >> while keeping it readable, this changes it to use strndup_user(). >> >> Obviously this is not a fast path, so the kmalloc() overhead >> can be disregarded. >> >> Fixes: 35951393bbff ("pktgen: Remove VLA usage") >> Signed-off-by: Arnd Bergmann <arnd@arndb.de> > > Applied, thanks.
Arnd: Thanks for the fix. On 03/13/2018 10:02 PM, Wang Jian wrote: >>> + kfree(buf); > free tb? buf is an array. > Wang: Thanks for the report. I already sent a patch to fix this: https://patchwork.kernel.org/patch/10281587/ -- Gustavo > On Wed, Mar 14, 2018 at 8:25 AM, David Miller <davem@davemloft.net> wrote: >> From: Arnd Bergmann <arnd@arndb.de> >> Date: Tue, 13 Mar 2018 21:58:39 +0100 >> >>> After the removal of the VLA, we get a harmless warning about a large >>> stack frame: >>> >>> net/core/pktgen.c: In function 'pktgen_if_write': >>> net/core/pktgen.c:1710:1: error: the frame size of 1076 bytes is larger than 1024 bytes [-Werror=frame-larger-than=] >>> >>> The function was previously shown to be safe despite hitting >>> the 1024 bye warning level. To get rid of the annoyging warning, >>> while keeping it readable, this changes it to use strndup_user(). >>> >>> Obviously this is not a fast path, so the kmalloc() overhead >>> can be disregarded. >>> >>> Fixes: 35951393bbff ("pktgen: Remove VLA usage") >>> Signed-off-by: Arnd Bergmann <arnd@arndb.de> >> >> Applied, thanks.
diff --git a/net/core/pktgen.c b/net/core/pktgen.c index de17a9f3e1f6..9216cf99b5a0 100644 --- a/net/core/pktgen.c +++ b/net/core/pktgen.c @@ -906,13 +906,14 @@ static ssize_t pktgen_if_write(struct file *file, i += len; if (debug) { - size_t copy = min_t(size_t, count, 1023); - char tb[1024]; - if (copy_from_user(tb, user_buffer, copy)) - return -EFAULT; - tb[copy] = 0; - pr_debug("%s,%lu buffer -:%s:-\n", - name, (unsigned long)count, tb); + size_t copy = min_t(size_t, count + 1, 1024); + char *tp = strndup_user(user_buffer, copy); + + if (IS_ERR(tp)) + return PTR_ERR(tp); + + pr_debug("%s,%zu buffer -:%s:-\n", name, count, tp); + kfree(buf); } if (!strcmp(name, "min_pkt_size")) {
After the removal of the VLA, we get a harmless warning about a large stack frame: net/core/pktgen.c: In function 'pktgen_if_write': net/core/pktgen.c:1710:1: error: the frame size of 1076 bytes is larger than 1024 bytes [-Werror=frame-larger-than=] The function was previously shown to be safe despite hitting the 1024 bye warning level. To get rid of the annoyging warning, while keeping it readable, this changes it to use strndup_user(). Obviously this is not a fast path, so the kmalloc() overhead can be disregarded. Fixes: 35951393bbff ("pktgen: Remove VLA usage") Signed-off-by: Arnd Bergmann <arnd@arndb.de> --- net/core/pktgen.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) -- 2.9.0