[PATCH] get rid of leak in compat_execve()

Even though copy_compat_strings() doesn't cache the pages,
copy_strings_kernel() and stuff indirectly called by e.g.
->load_binary() is doing that, so we need to drop the
cache contents in the end.

[found by WANG Cong <wangcong@zeuux.org>]

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

3 files changed, 11 insertions, 6 deletions

diff --git a/fs/compat.c b/fs/compat.c
index 332a869d2c53..ed43e17a5dc6 100644
--- a/fs/compat.c
+++ b/fs/compat.c
@@ -1405,7 +1405,7 @@ int compat_do_execve(char * filename,
                 /* execve success */
                 security_bprm_free(bprm);
                 acct_update_integrals(current);
-                kfree(bprm);
+                free_bprm(bprm);
                 return retval;
         }
 
@@ -1424,7 +1424,7 @@ out_file:
         }
 
 out_kfree:
-        kfree(bprm);
+        free_bprm(bprm);
 
 out_ret:
         return retval;
diff --git a/fs/exec.c b/fs/exec.c
index 1f8a24aa1f8b..3c2ba7ce11d4 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1251,6 +1251,12 @@ int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
 
 EXPORT_SYMBOL(search_binary_handler);
 
+void free_bprm(struct linux_binprm *bprm)
+{
+        free_arg_pages(bprm);
+        kfree(bprm);
+}
+
 /*
  * sys_execve() executes a new program.
  */
@@ -1320,17 +1326,15 @@ int do_execve(char * filename,
         retval = search_binary_handler(bprm,regs);
         if (retval >= 0) {
                 /* execve success */
-                free_arg_pages(bprm);
                 security_bprm_free(bprm);
                 acct_update_integrals(current);
-                kfree(bprm);
+                free_bprm(bprm);
                 if (displaced)
                         put_files_struct(displaced);
                 return retval;
         }
 
 out:
-        free_arg_pages(bprm);
         if (bprm->security)
                 security_bprm_free(bprm);
 
@@ -1344,7 +1348,7 @@ out_file:
                 fput(bprm->file);
         }
 out_kfree:
-        kfree(bprm);
+        free_bprm(bprm);
 
 out_files:
         if (displaced)
diff --git a/include/linux/binfmts.h b/include/linux/binfmts.h
index b512e48f6d8e..ee0ed48e8348 100644
--- a/include/linux/binfmts.h
+++ b/include/linux/binfmts.h
@@ -99,6 +99,7 @@ extern int copy_strings_kernel(int argc,char ** argv,struct linux_binprm *bprm);
 extern void compute_creds(struct linux_binprm *binprm);
 extern int do_coredump(long signr, int exit_code, struct pt_regs * regs);
 extern int set_binfmt(struct linux_binfmt *new);
+extern void free_bprm(struct linux_binprm *);
 
 #endif /* __KERNEL__ */
 #endif /* _LINUX_BINFMTS_H */