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From a2ef990ab5a6705a356d146dd773a3b359787497 Mon Sep 17 00:00:00 2001
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From: Xiaotian Feng <xtfeng@gmail.com>
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Date: Thu, 12 Jan 2012 17:17:08 -0800
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Subject: [PATCH] proc: fix null pointer deref in proc_pid_permission()
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get_proc_task() can fail to search the task and return NULL,
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put_task_struct() will then bomb the kernel with following oops:
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BUG: unable to handle kernel NULL pointer dereference at 0000000000000010
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IP: [<ffffffff81217d34>] proc_pid_permission+0x64/0xe0
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PGD 112075067 PUD 112814067 PMD 0
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Oops: 0002 [#1] PREEMPT SMP
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This is a regression introduced by commit 0499680a ("procfs: add hidepid=
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and gid= mount options"). The kernel should return -ESRCH if
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get_proc_task() failed.
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Signed-off-by: Xiaotian Feng <dannyfeng@tencent.com>
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Cc: Al Viro <viro@zeniv.linux.org.uk>
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Cc: Vasiliy Kulikov <segoon@openwall.com>
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Cc: Stephen Wilson <wilsons@start.ca>
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Acked-by: David Rientjes <rientjes@google.com>
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Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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---
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fs/proc/base.c | 2 ++
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1 files changed, 2 insertions(+), 0 deletions(-)
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diff --git a/fs/proc/base.c b/fs/proc/base.c
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index 8173dfd..5485a53 100644
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--- a/fs/proc/base.c
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+++ b/fs/proc/base.c
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@@ -654,6 +654,8 @@ static int proc_pid_permission(struct inode *inode, int mask)
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bool has_perms;
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task = get_proc_task(inode);
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+ if (!task)
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+ return -ESRCH;
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has_perms = has_pid_permissions(pid, task, 1);
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put_task_struct(task);
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--
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1.7.7.5
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