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authorKirill Korotaev <dev@sw.ru>2006-09-29 02:00:05 -0700
committerLinus Torvalds <torvalds@g5.osdl.org>2006-09-29 09:18:12 -0700
commit3b9b8ab65d8eed784b9164d03807cb2bda7b5cd6 (patch)
tree104c7b01768acd7e152cbf66e4868a73804e8af9
parentfc09561d6392771a392dea55c287de7e849b6b63 (diff)
downloadlinaro-lsk-3b9b8ab65d8eed784b9164d03807cb2bda7b5cd6.tar.gz
[PATCH] Fix unserialized task->files changing
Fixed race on put_files_struct on exec with proc. Restoring files on current on error path may lead to proc having a pointer to already kfree-d files_struct. ->files changing at exit.c and khtread.c are safe as exit_files() makes all things under lock. Found during OpenVZ stress testing. [akpm@osdl.org: add export] Signed-off-by: Pavel Emelianov <xemul@openvz.org> Signed-off-by: Kirill Korotaev <dev@openvz.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--fs/binfmt_elf.c6
-rw-r--r--fs/binfmt_misc.c6
-rw-r--r--fs/exec.c3
-rw-r--r--include/linux/file.h1
-rw-r--r--kernel/exit.c12
5 files changed, 18 insertions, 10 deletions
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index dfd8cfb7fb5..bb43da5cde5 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1038,10 +1038,8 @@ out_free_interp:
out_free_file:
sys_close(elf_exec_fileno);
out_free_fh:
- if (files) {
- put_files_struct(current->files);
- current->files = files;
- }
+ if (files)
+ reset_files_struct(current, files);
out_free_ph:
kfree(elf_phdata);
goto out;
diff --git a/fs/binfmt_misc.c b/fs/binfmt_misc.c
index 66ba137f866..1713c48fef5 100644
--- a/fs/binfmt_misc.c
+++ b/fs/binfmt_misc.c
@@ -215,10 +215,8 @@ _error:
bprm->interp_flags = 0;
bprm->interp_data = 0;
_unshare:
- if (files) {
- put_files_struct(current->files);
- current->files = files;
- }
+ if (files)
+ reset_files_struct(current, files);
goto _ret;
}
diff --git a/fs/exec.c b/fs/exec.c
index 97df6e0aeae..a8efe35176b 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -898,8 +898,7 @@ int flush_old_exec(struct linux_binprm * bprm)
return 0;
mmap_failed:
- put_files_struct(current->files);
- current->files = files;
+ reset_files_struct(current, files);
out:
return retval;
}
diff --git a/include/linux/file.h b/include/linux/file.h
index 9f7c2513866..74183e6f7f4 100644
--- a/include/linux/file.h
+++ b/include/linux/file.h
@@ -112,5 +112,6 @@ struct task_struct;
struct files_struct *get_files_struct(struct task_struct *);
void FASTCALL(put_files_struct(struct files_struct *fs));
+void reset_files_struct(struct task_struct *, struct files_struct *);
#endif /* __LINUX_FILE_H */
diff --git a/kernel/exit.c b/kernel/exit.c
index d891883420f..4b6fb054b25 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -487,6 +487,18 @@ void fastcall put_files_struct(struct files_struct *files)
EXPORT_SYMBOL(put_files_struct);
+void reset_files_struct(struct task_struct *tsk, struct files_struct *files)
+{
+ struct files_struct *old;
+
+ old = tsk->files;
+ task_lock(tsk);
+ tsk->files = files;
+ task_unlock(tsk);
+ put_files_struct(old);
+}
+EXPORT_SYMBOL(reset_files_struct);
+
static inline void __exit_files(struct task_struct *tsk)
{
struct files_struct * files = tsk->files;