[PATCH] proc: check vma->vm_file before dereferencing

From: Stanislav Kinsbursky
Date: Mon Oct 15 2012 - 11:28:00 EST


It can be equal to NULL.

Signed-off-by: Stanislav Kinsbursky <skinsbursky@xxxxxxxxxxxxx>
---
fs/proc/base.c | 5 +++--
1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 144a967..74fc562 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1770,8 +1770,9 @@ 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);

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