* [PATCH v2] selinux: hooks: use kmalloc() to allocate path buffer
@ 2026-05-31 15:15 Mike Rapoport
2026-05-31 16:18 ` David Laight
0 siblings, 1 reply; 3+ messages in thread
From: Mike Rapoport @ 2026-05-31 15:15 UTC (permalink / raw)
To: Paul Moore, Stephen Smalley
Cc: David Laight, Mike Rapoport, Ondrej Mosnacek,
Venkat Rao Bagalkote, selinux, linux-kernel
From: "Mike Rapoport (Microsoft)" <rppt@kernel.org>
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) <rppt@kernel.org>
---
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);
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;
}
--
2.53.0
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH v2] selinux: hooks: use kmalloc() to allocate path buffer
2026-05-31 15:15 [PATCH v2] selinux: hooks: use kmalloc() to allocate path buffer Mike Rapoport
@ 2026-05-31 16:18 ` David Laight
2026-05-31 16:55 ` Mike Rapoport
0 siblings, 1 reply; 3+ messages in thread
From: David Laight @ 2026-05-31 16:18 UTC (permalink / raw)
To: Mike Rapoport
Cc: Paul Moore, Stephen Smalley, Ondrej Mosnacek,
Venkat Rao Bagalkote, selinux, linux-kernel
On Sun, 31 May 2026 18:15:02 +0300
Mike Rapoport <rppt@kernel.org> wrote:
> From: "Mike Rapoport (Microsoft)" <rppt@kernel.org>
>
> 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) <rppt@kernel.org>
> ---
> 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;
> }
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v2] selinux: hooks: use kmalloc() to allocate path buffer
2026-05-31 16:18 ` David Laight
@ 2026-05-31 16:55 ` Mike Rapoport
0 siblings, 0 replies; 3+ messages in thread
From: Mike Rapoport @ 2026-05-31 16:55 UTC (permalink / raw)
To: David Laight
Cc: Paul Moore, Stephen Smalley, Ondrej Mosnacek,
Venkat Rao Bagalkote, selinux, linux-kernel
On Sun, May 31, 2026 at 05:18:11PM +0100, David Laight wrote:
> On Sun, 31 May 2026 18:15:02 +0300
> Mike Rapoport <rppt@kernel.org> wrote:
>
> > From: "Mike Rapoport (Microsoft)" <rppt@kernel.org>
> >
> > 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) <rppt@kernel.org>
> > ---
> > 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.
oops
--
Sincerely yours,
Mike.
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