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Received: from willy by casper.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1s1HIJ-0000000BAgI-3G4G; Mon, 29 Apr 2024 03:03:07 +0000 Date: Mon, 29 Apr 2024 04:03:07 +0100 From: Matthew Wilcox To: Dan Carpenter Cc: Christoph Lameter , Peter Zijlstra , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Vlastimil Babka , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org, Bartosz Golaszewski Subject: Re: [PATCH] mm/slab: make __free(kfree) accept error pointers Message-ID: References: <285fee25-b447-47a1-9e00-3deb8f9af53e@moroto.mountain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <285fee25-b447-47a1-9e00-3deb8f9af53e@moroto.mountain> X-Rspamd-Queue-Id: EB09BA0005 X-Rspam-User: X-Rspamd-Server: rspam03 X-Stat-Signature: mxc6owzmprkror1goscworhyiyn3gda9 X-HE-Tag: 1714359796-785030 X-HE-Meta: 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 8tYQhewF za19QmlUkVNFFjubLIA75E9b7NCco8xSW0LJM/OVQaEJdfMc7RHNvFXdmiCLO2DtKu6lptTzY5MQfjX2FtFYVRcwcn6pFTjN9UDokkW9/1B5VaP6vlkkcF6ATlc1MhUiWNkuQ3tAcMVPcLcOvwnlTVGzG6lrn0zF2u4XT2+W4Tl3IImn14fvvfc1zy4jLPAnUE7IG9BeJKn0DfKKUGOCjW3lXmwauyvA+Mq3cx+2sMQ2gKKAFz3ckneG5WB8XTYWc7EcH+EDjeKHkCCEpmSgzrEsUcxy1DyUrDnTp4HLPDe6z5VgNMVPyYR864T/DRtwjE/tm+ZWSnTexccutHOESHg0w/sWRdcWBkzHVqF3bR3KgWiAOWwhLlIszYw== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Sun, Apr 28, 2024 at 05:26:44PM +0300, Dan Carpenter wrote: > Currently, if an automatically freed allocation is an error pointer that > will lead to a crash. An example of this is in wm831x_gpio_dbg_show(). > > 171 char *label __free(kfree) = gpiochip_dup_line_label(chip, i); > 172 if (IS_ERR(label)) { > 173 dev_err(wm831x->dev, "Failed to duplicate label\n"); > 174 continue; > 175 } > > The auto clean up function should check for error pointers as well, > otherwise we're going to keep hitting issues like this. > > Fixes: 54da6a092431 ("locking: Introduce __cleanup() based infrastructure") > Cc: > Signed-off-by: Dan Carpenter > --- > Obviously, the fixes tag isn't very fair but it will tell the -stable > tools how far to backport this. > > include/linux/slab.h | 4 ++-- > 1 files changed, 2 insertions(+), 2 deletions(-) > > diff --git a/include/linux/slab.h b/include/linux/slab.h > index 4cc37ef22aae..5f5766219375 100644 > --- a/include/linux/slab.h > +++ b/include/linux/slab.h > @@ -279,7 +279,7 @@ void kfree(const void *objp); > void kfree_sensitive(const void *objp); > size_t __ksize(const void *objp); > > -DEFINE_FREE(kfree, void *, if (_T) kfree(_T)) > +DEFINE_FREE(kfree, void *, if (!IS_ERR_OR_NULL(_T)) kfree(_T)) Wait, why do we check 'if (_T)' at all? kfree() already handles NULL pointers just fine. I wouldn't be averse to making it handle error pointers either. > -DEFINE_FREE(kvfree, void *, if (_T) kvfree(_T)) > +DEFINE_FREE(kvfree, void *, if (!IS_ERR_OR_NULL(_T)) kvfree(_T)) Ditto kvfree(). Fixing kfree() would fix both of these.