proc: do proper range check on readdir offset, CVE-2011-1593
 

From: Linus Torvalds <torvalds@linux-foundation.org>

CVE-2011-1593

BugLink: https://bugs.launchpad.net/bugs/784727

Released until now with stable versions 2.6.27.59, 2.6.32.39, 2.6.33.12,
2.6.35.13, 2.6.38.4

Rather than pass in some random truncated offset to the pid-related
functions, check that the offset is in range up-front.

This is just cleanup, the previous commit fixed the real problem.

Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(cherry-picked from commit d8bdc59f215e62098bc5b4256fd9928bf27053a1 upstream)
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski@canonical.com>
---
fs/proc/base.c | 9 +++++++--
1 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 1898c49..a91dc82 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -2560,11 +2560,16 @@ static int proc_pid_fill_cache(struct file *filp, void *dirent, filldir_t filldi
/* for the /proc/ directory itself, after non-process stuff has been done */
int proc_pid_readdir(struct file * filp, void * dirent, filldir_t filldir)
{
- unsigned int nr = filp->f_pos - FIRST_PROCESS_ENTRY;
- struct task_struct *reaper = get_proc_task(filp->f_path.dentry->d_inode);
+ unsigned int nr;
+ struct task_struct *reaper;
struct tgid_iter iter;
struct pid_namespace *ns;

+ if (filp->f_pos >= PID_MAX_LIMIT + TGID_OFFSET)
+ goto out_no_task;
+ nr = filp->f_pos - FIRST_PROCESS_ENTRY;
+
+ reaper = get_proc_task(filp->f_path.dentry->d_inode);
if (!reaper)
goto out_no_task;

--
1.7.0.4


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