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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4909ca6e124sm191663255e9.7.2026.05.31.09.18.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 31 May 2026 09:18:12 -0700 (PDT) Date: Sun, 31 May 2026 17:18:11 +0100 From: David Laight To: Mike Rapoport Cc: Paul Moore , Stephen Smalley , Ondrej Mosnacek , Venkat Rao Bagalkote , selinux@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] selinux: hooks: use kmalloc() to allocate path buffer Message-ID: <20260531171811.16abb087@pumpkin> In-Reply-To: <20260531151502.1467515-1-rppt@kernel.org> References: <20260531151502.1467515-1-rppt@kernel.org> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Sun, 31 May 2026 18:15:02 +0300 Mike Rapoport wrote: > From: "Mike Rapoport (Microsoft)" > > selinux_genfs_get_sid() allocates memory for a path with __get_free_page(). > > Such usage does not require a "page" and the size of the buffer should > actually be PATH_MAX which may be less than PAGE_SIZE on some > architectures. > > Replace __get_free_page() for allocation of a path buffer with kmalloc() > and make it explicit that the buffer size is PATH_MAX. > > Signed-off-by: Mike Rapoport (Microsoft) > --- > v2 changes: > * explicitly use kmalloc() with PATH_MAX > > security/selinux/hooks.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c > index 0f704380a8c8..19493198ece1 100644 > --- a/security/selinux/hooks.c > +++ b/security/selinux/hooks.c > @@ -1336,11 +1336,11 @@ static int selinux_genfs_get_sid(struct dentry *dentry, > struct super_block *sb = dentry->d_sb; > char *buffer, *path; > > - buffer = (char *)__get_free_page(GFP_KERNEL); > + buffer = kmalloc(GFP_KERNEL, PATH_MAX); At least get the args in the right order. > if (!buffer) > return -ENOMEM; > > - path = dentry_path_raw(dentry, buffer, PAGE_SIZE); > + path = dentry_path_raw(dentry, buffer, PATH_MAX); > if (IS_ERR(path)) > rc = PTR_ERR(path); > else { > @@ -1361,7 +1361,7 @@ static int selinux_genfs_get_sid(struct dentry *dentry, > rc = 0; > } > } > - free_page((unsigned long)buffer); > + kfree(buffer); > return rc; > } >