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Mon, 9 Dec 2024 13:19:17 +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 iv6OHVXuVmf+aAAAD6G6ig (envelope-from ); Mon, 09 Dec 2024 13:19:17 +0000 Message-ID: <9e4c39b5-387a-428d-9353-370654337cc9@suse.cz> Date: Mon, 9 Dec 2024 14:19:17 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm: correctly reference merged VMA Content-Language: en-US To: Lorenzo Stoakes , Andrew Morton Cc: "Liam R . Howlett" , Jann Horn , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20241206215229.244413-1-lorenzo.stoakes@oracle.com> 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: <20241206215229.244413-1-lorenzo.stoakes@oracle.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: F363480008 X-Rspam-User: X-Stat-Signature: dyayyms6hnpagwcksm4pak97fttsjsqh X-HE-Tag: 1733750319-259699 X-HE-Meta: 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 oUiBA1tN VDT6vZSvk32++l4v9bykrkXbGdh5EH8ucN9NEbtDhprOo+sEPy3iEX1LLoGMfoSMFc2ex0MHoMpYlXM84/tFb+UohYZdMIVYOuFH/+szqgPHanTVeP+CtLGZafJAsyy5GB3pZI6k15iu4RNF2MyfyT4AP7G5J3cWUJad3ovhfCGLyij7hOqOy3pXO3KqngYes3LWf+2sRd9UZ2yFDJ2JtSZMlQT1q4byjIr42QIP9qdzh1fyBT02iTYm8F51V18SES16KPKPs0hLvEDEGXgeAfV6otwO1vVk/Kd7AgRkTcMzJnkCBttQNs7PY1q6WnOOFfJr3U4aQ1tDy801xUwxJkQzmoCQlNVXtGtxzD8cFoGeBJQD1ED5fPH3K5HwDhsxcIDFNdyp93ZYDV7K+an2wPV5xh2flqFbSxZ3e X-Bogosity: Ham, tests=bogofilter, spamicity=0.000058, 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 12/6/24 22:52, Lorenzo Stoakes wrote: > On second merge attempt on mmap() we incorrectly discard the possibly > merged VMA, resulting in a possible use-after-free (and most certainly a > reference to the wrong VMA) in this instance in the subsequent > __mmap_complete() invocation. > > Correct this mistake by reassigning vma correctly if a merge succeeds in > this case. > > Suggested-by: Jann Horn > Reported-by: syzbot+91cf8da9401355f946c3@syzkaller.appspotmail.com > Closes: https://lore.kernel.org/all/67536a25.050a0220.a30f1.0149.GAE@google.com/ > Fixes: 5ac87a885aec ("mm: defer second attempt at merge on mmap()") FFS, who reviewed that patch? > Signed-off-by: Lorenzo Stoakes Reviewed-by: Vlastimil Babka (copy/pasted from "git show 5ac87a885aec") > --- > mm/vma.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/mm/vma.c b/mm/vma.c > index 8a454a7bbc80..1ec349141f5e 100644 > --- a/mm/vma.c > +++ b/mm/vma.c > @@ -2460,10 +2460,13 @@ unsigned long __mmap_region(struct file *file, unsigned long addr, > > /* If flags changed, we might be able to merge, so try again. */ > if (map.retry_merge) { > + struct vm_area_struct *merged; > VMG_MMAP_STATE(vmg, &map, vma); > > vma_iter_config(map.vmi, map.addr, map.end); > - vma_merge_existing_range(&vmg); > + merged = vma_merge_existing_range(&vmg); > + if (merged) > + vma = merged; > } > > __mmap_complete(&map, vma); > -- > 2.47.1