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| author | David Howells <dhowells@redhat.com> | 2008-11-14 10:39:19 +1100 |
|---|---|---|
| committer | James Morris <jmorris@namei.org> | 2008-11-14 10:39:19 +1100 |
| commit | c69e8d9c01db2adc503464993c358901c9af9de4 (patch) | |
| tree | bed94aaa9aeb7a7834d1c880f72b62a11a752c78 /fs/binfmt_elf_fdpic.c | |
| parent | 86a264abe542cfececb4df129bc45a0338d8cdb9 (diff) | |
| download | lwn-c69e8d9c01db2adc503464993c358901c9af9de4.tar.gz lwn-c69e8d9c01db2adc503464993c358901c9af9de4.zip | |
CRED: Use RCU to access another task's creds and to release a task's own creds
Use RCU to access another task's creds and to release a task's own creds.
This means that it will be possible for the credentials of a task to be
replaced without another task (a) requiring a full lock to read them, and (b)
seeing deallocated memory.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: James Morris <jmorris@namei.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
Diffstat (limited to 'fs/binfmt_elf_fdpic.c')
| -rw-r--r-- | fs/binfmt_elf_fdpic.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/fs/binfmt_elf_fdpic.c b/fs/binfmt_elf_fdpic.c index 1f6e8c023b4c..45dabd59936f 100644 --- a/fs/binfmt_elf_fdpic.c +++ b/fs/binfmt_elf_fdpic.c @@ -1414,6 +1414,7 @@ static void fill_prstatus(struct elf_prstatus *prstatus, static int fill_psinfo(struct elf_prpsinfo *psinfo, struct task_struct *p, struct mm_struct *mm) { + const struct cred *cred; unsigned int i, len; /* first copy the parameters from user space */ @@ -1441,8 +1442,11 @@ static int fill_psinfo(struct elf_prpsinfo *psinfo, struct task_struct *p, psinfo->pr_zomb = psinfo->pr_sname == 'Z'; psinfo->pr_nice = task_nice(p); psinfo->pr_flag = p->flags; - SET_UID(psinfo->pr_uid, p->cred->uid); - SET_GID(psinfo->pr_gid, p->cred->gid); + rcu_read_lock(); + cred = __task_cred(p); + SET_UID(psinfo->pr_uid, cred->uid); + SET_GID(psinfo->pr_gid, cred->gid); + rcu_read_unlock(); strncpy(psinfo->pr_fname, p->comm, sizeof(psinfo->pr_fname)); return 0; |