From 05f564849d49499ced97913a0914b5950577d07d Mon Sep 17 00:00:00 2001 From: Stanislav Kinsbursky Date: Mon, 26 Nov 2012 16:29:42 -0800 Subject: [PATCH] proc: check vma->vm_file before dereferencing Commit 7b540d0646ce ("proc_map_files_readdir(): don't bother with grabbing files") switched proc_map_files_readdir() to use @f_mode directly instead of grabbing @file reference, but same time the test for @vm_file presence was lost leading to nil dereference. The patch brings the test back. The all proc_map_files feature is CONFIG_CHECKPOINT_RESTORE wrapped (which is set to 'n' by default) so the bug doesn't affect regular kernels. The regression is 3.7-rc1 only as far as I can tell. [gorcunov@openvz.org: provided changelog] Signed-off-by: Stanislav Kinsbursky Acked-by: Cyrill Gorcunov Cc: Al Viro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/proc/base.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/fs/proc/base.c b/fs/proc/base.c index 3c231adf8450..9e28356a959a 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -1877,8 +1877,9 @@ static struct dentry *proc_map_files_lookup(struct inode *dir, if (!vma) goto out_no_vma; - result = proc_map_files_instantiate(dir, dentry, task, - (void *)(unsigned long)vma->vm_file->f_mode); + if (vma->vm_file) + result = proc_map_files_instantiate(dir, dentry, task, + (void *)(unsigned long)vma->vm_file->f_mode); out_no_vma: up_read(&mm->mmap_sem); -- 2.20.1