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Tue, 30 Apr 2024 12:09:10 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id azLpJ2bfMGa+FwAAD6G6ig (envelope-from ); Tue, 30 Apr 2024 12:09:10 +0000 Message-ID: <6a10be7d-b556-42a9-852c-b6ed821ec41e@suse.cz> Date: Tue, 30 Apr 2024 14:09:10 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/slab: make __free(kfree) accept error pointers Content-Language: en-US To: Matthew Wilcox , Dan Carpenter Cc: Christoph Lameter , Peter Zijlstra , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org, Bartosz Golaszewski , "Lameter, Christopher" References: <285fee25-b447-47a1-9e00-3deb8f9af53e@moroto.mountain> From: Vlastimil Babka Autocrypt: addr=vbabka@suse.cz; keydata= xsFNBFZdmxYBEADsw/SiUSjB0dM+vSh95UkgcHjzEVBlby/Fg+g42O7LAEkCYXi/vvq31JTB KxRWDHX0R2tgpFDXHnzZcQywawu8eSq0LxzxFNYMvtB7sV1pxYwej2qx9B75qW2plBs+7+YB 87tMFA+u+L4Z5xAzIimfLD5EKC56kJ1CsXlM8S/LHcmdD9Ctkn3trYDNnat0eoAcfPIP2OZ+ 9oe9IF/R28zmh0ifLXyJQQz5ofdj4bPf8ecEW0rhcqHfTD8k4yK0xxt3xW+6Exqp9n9bydiy tcSAw/TahjW6yrA+6JhSBv1v2tIm+itQc073zjSX8OFL51qQVzRFr7H2UQG33lw2QrvHRXqD Ot7ViKam7v0Ho9wEWiQOOZlHItOOXFphWb2yq3nzrKe45oWoSgkxKb97MVsQ+q2SYjJRBBH4 8qKhphADYxkIP6yut/eaj9ImvRUZZRi0DTc8xfnvHGTjKbJzC2xpFcY0DQbZzuwsIZ8OPJCc LM4S7mT25NE5kUTG/TKQCk922vRdGVMoLA7dIQrgXnRXtyT61sg8PG4wcfOnuWf8577aXP1x 6mzw3/jh3F+oSBHb/GcLC7mvWreJifUL2gEdssGfXhGWBo6zLS3qhgtwjay0Jl+kza1lo+Cv BB2T79D4WGdDuVa4eOrQ02TxqGN7G0Biz5ZLRSFzQSQwLn8fbwARAQABzSBWbGFzdGltaWwg QmFia2EgPHZiYWJrYUBzdXNlLmN6PsLBlAQTAQoAPgIbAwULCQgHAwUVCgkICwUWAgMBAAIe AQIXgBYhBKlA1DSZLC6OmRA9UCJPp+fMgqZkBQJkBREIBQkRadznAAoJECJPp+fMgqZkNxIQ ALZRqwdUGzqL2aeSavbum/VF/+td+nZfuH0xeWiO2w8mG0+nPd5j9ujYeHcUP1edE7uQrjOC Gs9sm8+W1xYnbClMJTsXiAV88D2btFUdU1mCXURAL9wWZ8Jsmz5ZH2V6AUszvNezsS/VIT87 AmTtj31TLDGwdxaZTSYLwAOOOtyqafOEq+gJB30RxTRE3h3G1zpO7OM9K6ysLdAlwAGYWgJJ V4JqGsQ/lyEtxxFpUCjb5Pztp7cQxhlkil0oBYHkudiG8j1U3DG8iC6rnB4yJaLphKx57NuQ PIY0Bccg+r9gIQ4XeSK2PQhdXdy3UWBr913ZQ9AI2usid3s5vabo4iBvpJNFLgUmxFnr73SJ KsRh/2OBsg1XXF/wRQGBO9vRuJUAbnaIVcmGOUogdBVS9Sun/Sy4GNA++KtFZK95U7J417/J Hub2xV6Ehc7UGW6fIvIQmzJ3zaTEfuriU1P8ayfddrAgZb25JnOW7L1zdYL8rXiezOyYZ8Fm ZyXjzWdO0RpxcUEp6GsJr11Bc4F3aae9OZtwtLL/jxc7y6pUugB00PodgnQ6CMcfR/HjXlae h2VS3zl9+tQWHu6s1R58t5BuMS2FNA58wU/IazImc/ZQA+slDBfhRDGYlExjg19UXWe/gMcl De3P1kxYPgZdGE2eZpRLIbt+rYnqQKy8UxlszsBNBFsZNTUBCACfQfpSsWJZyi+SHoRdVyX5 J6rI7okc4+b571a7RXD5UhS9dlVRVVAtrU9ANSLqPTQKGVxHrqD39XSw8hxK61pw8p90pg4G /N3iuWEvyt+t0SxDDkClnGsDyRhlUyEWYFEoBrrCizbmahOUwqkJbNMfzj5Y7n7OIJOxNRkB IBOjPdF26dMP69BwePQao1M8Acrrex9sAHYjQGyVmReRjVEtv9iG4DoTsnIR3amKVk6si4Ea X/mrapJqSCcBUVYUFH8M7bsm4CSxier5ofy8jTEa/CfvkqpKThTMCQPNZKY7hke5qEq1CBk2 wxhX48ZrJEFf1v3NuV3OimgsF2odzieNABEBAAHCwXwEGAEKACYCGwwWIQSpQNQ0mSwujpkQ PVAiT6fnzIKmZAUCZAUSmwUJDK5EZgAKCRAiT6fnzIKmZOJGEACOKABgo9wJXsbWhGWYO7mD 8R8mUyJHqbvaz+yTLnvRwfe/VwafFfDMx5GYVYzMY9TWpA8psFTKTUIIQmx2scYsRBUwm5VI EurRWKqENcDRjyo+ol59j0FViYysjQQeobXBDDE31t5SBg++veI6tXfpco/UiKEsDswL1WAr tEAZaruo7254TyH+gydURl2wJuzo/aZ7Y7PpqaODbYv727Dvm5eX64HCyyAH0s6sOCyGF5/p eIhrOn24oBf67KtdAN3H9JoFNUVTYJc1VJU3R1JtVdgwEdr+NEciEfYl0O19VpLE/PZxP4wX PWnhf5WjdoNI1Xec+RcJ5p/pSel0jnvBX8L2cmniYnmI883NhtGZsEWj++wyKiS4NranDFlA HdDM3b4lUth1pTtABKQ1YuTvehj7EfoWD3bv9kuGZGPrAeFNiHPdOT7DaXKeHpW9homgtBxj 8aX/UkSvEGJKUEbFL9cVa5tzyialGkSiZJNkWgeHe+jEcfRT6pJZOJidSCdzvJpbdJmm+eED w9XOLH1IIWh7RURU7G1iOfEfmImFeC3cbbS73LQEFGe1urxvIH5K/7vX+FkNcr9ujwWuPE9b 1C2o4i/yZPLXIVy387EjA6GZMqvQUFuSTs/GeBcv0NjIQi8867H3uLjz+mQy63fAitsDwLmR EP+ylKVEKb0Q2A== In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 876801C0010 X-Stat-Signature: hbkq18wcxdebb97i3mg4g8ohdjzbhk1a X-Rspam-User: X-HE-Tag: 1714478952-944974 X-HE-Meta: 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 OThRc4Ij nlo6vMVyTWD9jCquCENWnNWxmnend5Dt3NUxLRLhq1uQgAxKiqLQdvGsRAs8BLP9ITc3zGzd+e1Dn5XFBCakJtlFD8DxTzPVacUWQQiYnlpnCcefMW5VZ26z7ot9VWP1/WsWotklIgiRoLEivau8QwBCVQlAwX4wnO1dLKUOCIeDBIsdhOVTos9VPUWmpuPX+jJg+Pdvn8GtAm7Th3btdUI+rXFR9xiMGe4eNsnJROR9ID/LW1eQM4MaMgKbtg7qRRKenfwzeUqa00dyHqfo5WZeM03ExacNOrdq0HAs9iRiqKQTDQhGO2pfGvxu0mo0olav+g9l2pNRdjZFs7kbBxfdvsJt+hRFz/dnO5VhL0q0wAV89Ka6ag026pwtFWFz3FCOF6GAiIxT1Ae/fyS4U7wF/OUTYwMYP9YsciWOctryoreKtP9LVx6+gC9Z64lKkZeFql/R5ZXMAnVaEVe9PPem47f3d0XrhSVYQhKuINCV4CbH0QjI0WFeScQ== 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 4/29/24 5:03 AM, Matthew Wilcox wrote: > 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. Making kfree() handle IS_ERR() is perhaps a discussion for something else than a stable fix. But Christoph has a point that kfree() checks ZERO_OR_NULL_PTR. Here we check IS_ERR_OR_NULL. How about we checked only IS_ERR here so it makes some sense? >> -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. ZERO and NULL should be both false for is_vmalloc_addr() so ultimately kfree() will handle those, so we could also do only IS_ERR here?