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authorDavid Howells <dhowells@redhat.com>2008-11-13 18:39:19 -0500
committerJames Morris <jmorris@namei.org>2008-11-13 18:39:19 -0500
commitc69e8d9c01db2adc503464993c358901c9af9de4 (patch)
treebed94aaa9aeb7a7834d1c880f72b62a11a752c78 /fs/binfmt_elf_fdpic.c
parent86a264abe542cfececb4df129bc45a0338d8cdb9 (diff)
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.c8
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,
1414static int fill_psinfo(struct elf_prpsinfo *psinfo, struct task_struct *p, 1414static int fill_psinfo(struct elf_prpsinfo *psinfo, struct task_struct *p,
1415 struct mm_struct *mm) 1415 struct mm_struct *mm)
1416{ 1416{
1417 const struct cred *cred;
1417 unsigned int i, len; 1418 unsigned int i, len;
1418 1419
1419 /* first copy the parameters from user space */ 1420 /* first copy the parameters from user space */
@@ -1441,8 +1442,11 @@ static int fill_psinfo(struct elf_prpsinfo *psinfo, struct task_struct *p,
1441 psinfo->pr_zomb = psinfo->pr_sname == 'Z'; 1442 psinfo->pr_zomb = psinfo->pr_sname == 'Z';
1442 psinfo->pr_nice = task_nice(p); 1443 psinfo->pr_nice = task_nice(p);
1443 psinfo->pr_flag = p->flags; 1444 psinfo->pr_flag = p->flags;
1444 SET_UID(psinfo->pr_uid, p->cred->uid); 1445 rcu_read_lock();
1445 SET_GID(psinfo->pr_gid, p->cred->gid); 1446 cred = __task_cred(p);
1447 SET_UID(psinfo->pr_uid, cred->uid);
1448 SET_GID(psinfo->pr_gid, cred->gid);
1449 rcu_read_unlock();
1446 strncpy(psinfo->pr_fname, p->comm, sizeof(psinfo->pr_fname)); 1450 strncpy(psinfo->pr_fname, p->comm, sizeof(psinfo->pr_fname));
1447 1451
1448 return 0; 1452 return 0;