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b=RWHqK3S3qatsdfVyfkwJd+wmD6PBE+gLSXhLcog0Et/IwzOgkm8aYa6gQI9jitp49 bYl3JbBm7vyk3NIM1Vati07UdXPc8CkCM/lMNiC3R26e2tV3ZiMiWfrZL+lO6C3MAw 9iddEyT16tjnC6r//StpgqZQfQicqQq2qaSHsxv36YsbsEshJsOl+gIHVdn7aF+yTe 27DLMb7VBJSNSG0PTk5Qcs2g0LwY3qTQaeJZQeYRZXSggYTtOiPSqrVdSi6p4jtoBQ eITXrRXA7giOLSBJsd3XqFqQeV2aJjDEO4Df9sjqXgi+zFxpQecINrhcroxQQdES+c N2bjhIrEcEGSg== Message-ID: Date: Tue, 27 Oct 2026 10:51:00 +0100 X-Archived-By: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 05/16] hugetlbfs: enforce F_SEAL_EXEC in setattr To: sashiko-reviews@lists.linux.dev, Andrew Morton , Gregory Price , Zi Yan , Joshua Hahn , Rakie Kim , Ying Huang , Johannes Weiner , Vladimir Davydov , Michal Hocko , Hugh Dickins , Baolin Wang , Lukas Czerner , Carlos Maiolino , Christian Brauner , Jan Kara , Daniel Verkamp , Jeff Xu , Muchun Song , Oscar Salvador , David Stevens , "Matthew Wilcox (Oracle)" , William Kucharski , Chris Li , Kairui Song , Nhat Pham , Miaohe Lin , Naoya Horiguchi Cc: linux-mm@kvack.org, Eva Kurchatova References: <20261026-fixes_shmem-v1-0-703206d5fa0c@kernel.org> <20261026-fixes_shmem-v1-5-703206d5fa0c@kernel.org> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: B965F40006 X-Stat-Signature: peiumr4zcfnse9438n6xsw9te7fcbdra X-Rspamd-Server: rspam04 X-Spam-Status: No, score=-12.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=4.0.1 X-Rspam-User: X-HE-Tag: 1793094798-29835 X-HE-Meta: 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 NHcdpURG 3/DnbNaUJBcpZ/4xD1jkIWcY45M4knrRSnBhU/+lJ2J8w3WbCY6R21BVcGxONDfz29CFhEsDeXX1UoeQgr3lmkYFtj/Y19mb76ctpCz84YfGO+o9KFNgblgVyqUKZy0Y5dt9s8+vxG65yhyjSg3U/VoW7wbLH0zTNQ5WQeXKIqDEsS+E6ikjJ/HerBMVedYQ/RdwrZL/QRCaPsO/t9XUF8XdocHlI2DA14cls8QqLReLlb6936OT+0TyMsElvuDKXwy+bkm02L5/zvnhLZWL+P2AC5qAPVyajkCsgjwUcH/sLtgP9vC6RRVzwETIoQIji+djw627iJuoLKeIP0q1ExdndX1mDFqhNG/Vi8hNzhhdfwUPFOQMKazsVirQEqH7gekuR8ilt5C/NyvT7ckn1hKbxTm0pYXS3nd8mxOZ4HzLevMexJpaRn82l5aq4dftSf6QUjJ9HVeS9/YjVVMBcvjIWBQMzmUUOPwQnIqdCJPZvpLxLrUOf58AmtAlJlxfYlkcxsfxQhL4nkyfpMJvSYEUBEucreP2/Alu5f6TSOYB9qVU= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On 10/27/26 03:22, sashiko-bot@kernel.org wrote: > Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider: > - [Medium] hugetlbfs: uninitialized info->seals read in hugetlbfs_setattr() on root dir > -- > > commit dfab7a0d71278312f805e82ce52518a8ea2f538d > Author: Eva Kurchatova > > hugetlbfs: enforce F_SEAL_EXEC in setattr > > This patch updates hugetlbfs_setattr() to call memfd_check_seals_mode() when > ATTR_MODE is set so that fchmod() cannot modify execute bits on a hugetlbfs > memfd sealed with F_SEAL_EXEC. > > Link: https://patch.msgid.link/20260629180247.2343229-1-eva.kurchatova@virtuozzo.com > >> diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c >> index 6656807ce4377..7f5c3962b5d56 100644 >> --- a/fs/hugetlbfs/inode.c >> +++ b/fs/hugetlbfs/inode.c > > [ ... ] > >> @@ -841,6 +842,13 @@ static int hugetlbfs_setattr(const struct mnt_idmap *idmap, >> if (error) >> return error; >> >> + if (ia_valid & ATTR_MODE) { >> + error = memfd_check_seals_mode(info->seals, inode->i_mode, >> + attr->ia_mode); >> + if (error) >> + return error; >> + } > > [Severity: Medium] > Can this read uninitialized or stale slab memory from info->seals when > chmod() is called on a hugetlbfs root directory? > > hugetlbfs_dir_inode_operations wires .setattr to hugetlbfs_setattr(). Unlike > hugetlbfs_get_inode(), which sets info->seals = F_SEAL_SEAL, > hugetlbfs_get_root() allocates the root directory inode via new_inode() -> > hugetlbfs_alloc_inode() without initializing HUGETLBFS_I(inode)->seals: > > fs/hugetlbfs/inode.c:hugetlbfs_get_root() { > inode = new_inode(sb); > if (inode) { > ... > inode->i_op = &hugetlbfs_dir_inode_operations; > inode->i_fop = &simple_dir_operations; > HUGETLBFS_I(inode)->resv_map = NULL; > /* directory inodes start off with i_nlink == 2 (for "." entry) */ > inc_nlink(inode); > lockdep_annotate_inode_mutex_key(inode); > } > return inode; > } > > Because hugetlbfs_inode_cachep uses the init_once() slab constructor, which > only calls inode_init_once(&ei->vfs_inode), newly allocated or recycled > hugetlbfs_inode_info objects are not zeroed on allocation. > > Previously, hugetlbfs_setattr() only checked info->seals under ATTR_SIZE, > which is not reachable on directories. With the new ATTR_MODE check, changing > any execute/search bit on the mountpoint root directory reads info->seals > and can fail with -EPERM if the F_SEAL_EXEC bit is set in uninitialized > memory or left over from a previously freed sealed hugetlb memfd. > > Should hugetlbfs_get_root() also initialize HUGETLBFS_I(inode)->seals = > F_SEAL_SEAL? Shouldn't we just skip the check for directories? diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c index 7f5c3962b5d56..293c7965f4894 100644 --- a/fs/hugetlbfs/inode.c +++ b/fs/hugetlbfs/inode.c @@ -842,7 +842,7 @@ static int hugetlbfs_setattr(const struct mnt_idmap *idmap, if (error) return error; - if (ia_valid & ATTR_MODE) { + if (S_ISREG(inode->i_mode) && (ia_valid & ATTR_MODE)) { error = memfd_check_seals_mode(info->seals, inode->i_mode, attr->ia_mode); if (error) Because sealing of directories does not apply. Thoughts? -- Cheers, David