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[2003:e7:370b:be5f:73e3:aef8:4e62:7e25]) by smtp.gmail.com with ESMTPSA id i1-20020a05600c290100b003e89e3284fasm414421wmd.36.2023.03.10.09.16.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 10 Mar 2023 09:16:18 -0800 (PST) Date: Fri, 10 Mar 2023 18:16:17 +0100 From: Nils Hartmann To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH] Using MAP_SHARE_VALIDATE in mmap without fd Message-ID: <20230310171617.wqnqs42l2viwjsz5@archlinux> MIME-Version: 1.0 Content-Disposition: inline X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: D18231C0016 X-Stat-Signature: ysmufe31u4zu9pnhwyyj84jsqa84fgdz X-HE-Tag: 1678468580-408451 X-HE-Meta: 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 uiC53SBp 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 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: Hey, I have a rather simple question about the MAP_SHARED_VALIDATE flag in mmap. When used without a file pointer, EINVAL is returned. Is there a reason for this? I researched a bit but could not find anything. I attached a simple patch that adds MAP_SHARE_VALIDATE to the flags switch and checks for invalid flags. Signed-off-by: Nils Hartmann --- mm/mmap.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index 740b54be3..fd7db51af 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1196,6 +1196,7 @@ unsigned long do_mmap(struct file *file, unsigned long addr, { struct mm_struct *mm = current->mm; vm_flags_t vm_flags; + unsigned long flags_mask; int pkey = 0; validate_mm(mm); @@ -1266,14 +1267,14 @@ unsigned long do_mmap(struct file *file, unsigned long addr, if (mlock_future_check(mm, vm_flags, len)) return -EAGAIN; + flags_mask = LEGACY_MAP_MASK; if (file) { struct inode *inode = file_inode(file); - unsigned long flags_mask; if (!file_mmap_ok(file, inode, pgoff, len)) return -EOVERFLOW; - flags_mask = LEGACY_MAP_MASK | file->f_op->mmap_supported_flags; + flags_mask |= file->f_op->mmap_supported_flags; switch (flags & MAP_TYPE) { case MAP_SHARED: @@ -1327,6 +1328,10 @@ unsigned long do_mmap(struct file *file, unsigned long addr, } } else { switch (flags & MAP_TYPE) { + case MAP_SHARED_VALIDATE: + if (flags & ~flags_mask) + return -EOPNOTSUPP; + fallthrough; case MAP_SHARED: if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP)) return -EINVAL;