On 5/31/2018 2:28 AM, CHANDAN VN wrote:
> From: "sireesha.t" <sireesh...@samsung.com>
>
> Leak is caused because smack_inode_getsecurity() is allocating memory
> using kstrdup(). Though the security_release_secctx() is called, it
> would not free the allocated memory. Calling security_release_secctx is
> not relevant for this scenario as inode_getsecurity() does not provide a
> "secctx".
>
> Similar fix has been mainlined:
> https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/commit/?id=57e7ba04d422c3d41c8426380303ec9b7533ded9
>
> The fix is to replace the security_release_secctx() with a kfree()
>
> Below is the KMEMLEAK dump:
> unreferenced object 0xffffffc025e11c80 (size 64):
> comm "systemd-tmpfile", pid 2452, jiffies 4294894464 (age 235587.492s)
> hex dump (first 32 bytes):
> 53 79 73 74 65 6d 3a 3a 53 68 61 72 65 64 00 00 System::Shared..
> 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> backtrace:
> [<ffffff80081be770>] __save_stack_trace+0x28/0x34
> [<ffffff80081bedb8>] create_object+0x130/0x25c
> [<ffffff80088c82f8>] kmemleak_alloc+0x30/0x5c
> [<ffffff80081b3ef0>] __kmalloc_track_caller+0x1cc/0x2a8
> [<ffffff800818673c>] kstrdup+0x3c/0x6c
> [<ffffff80082d78b0>] smack_inode_getsecurity+0xcc/0xec
> [<ffffff80082d78f4>] smack_inode_getsecctx+0x24/0x44
> [<ffffff80082d5ea0>] security_inode_getsecctx+0x50/0x70
> [<ffffff800823bbcc>] kernfs_security_xattr_set+0x74/0xe0
> [<ffffff80081eafec>] __vfs_setxattr+0x74/0x90
> [<ffffff80081eb088>] __vfs_setxattr_noperm+0x80/0x1ac
> [<ffffff80081eb238>] vfs_setxattr+0x84/0xac
> [<ffffff80081eb374>] setxattr+0x114/0x178
> [<ffffff80081eb44c>] path_setxattr+0x74/0xb8
> [<ffffff80081ebdcc>] SyS_lsetxattr+0x10/0x1c
> [<ffffff800808310c>] __sys_trace_return+0x0/0x4
>
> Signed-off-by: sireesha.t <sireesh...@samsung.com>
> Signed-off-by: CHANDAN VN <chandan...@samsung.com>
Why not:
static int smack_inode_getsecctx(struct inode *inode, void **ctx, u32 *ctxlen)
{
- int len = 0;
- len = smack_inode_getsecurity(inode, XATTR_SMACK_SUFFIX, ctx, true);
+ int len = smack_inode_getsecurity(inode, XATTR_SMACK_SUFFIX, ctx,
false);
if (len < 0)
return len;
> ---
> fs/kernfs/inode.c | 3 ++-
> fs/nfsd/nfs4xdr.c | 2 +-
> 2 files changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/fs/kernfs/inode.c b/fs/kernfs/inode.c
> index a343039..53befb8 100644
> --- a/fs/kernfs/inode.c
> +++ b/fs/kernfs/inode.c
> @@ -369,7 +369,8 @@ static int kernfs_security_xattr_set(const struct
> xattr_handler *handler,
> mutex_unlock(&kernfs_mutex);
>
> if (secdata)
> - security_release_secctx(secdata, secdata_len);
> + kfree(secdata);
> +
> return error;
> }
>
> diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
> index aaa88c1..1e0dbe9 100644
> --- a/fs/nfsd/nfs4xdr.c
> +++ b/fs/nfsd/nfs4xdr.c
> @@ -2911,7 +2911,7 @@ static int get_parent_attributes(struct svc_export
> *exp, struct kstat *stat)
> out:
> #ifdef CONFIG_NFSD_V4_SECURITY_LABEL
> if (context)
> - security_release_secctx(context, contextlen);
> + kfree(context);
> #endif /* CONFIG_NFSD_V4_SECURITY_LABEL */
> kfree(acl);
> if (tempfh) {
