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[PATCH] security: reinstate extra ptrace security check in pagemap_read
From: James Morris <jmorris_at_nospam>Date: Tue Jul 08 2008 - 01:19:30 GMT
To: Stephen Smalley <sds@tycho.nsa.gov>
Please review. If it's ok, it should probably go into 2.6.26.
---
From: James Morris <jmorris@namei.org>
Date: Tue, 8 Jul 2008 10:10:47 +0900
Subject: [PATCH] security: reinstate extra ptrace security check in pagemap_read
Recent changes to the pagemap_read code removed a call to ptrace_may_attach(),
which is required to handle the case where a different process acquires the
mmap_sem semaphore after the first check.
Signed-off-by: James Morris <jmorris@namei.org>
---
fs/proc/task_mmu.c | 6 ++++++
1 files changed, 6 insertions(+), 0 deletions(-)
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index c492449..57cd6fa 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -685,6 +685,12 @@ static ssize_t pagemap_read(struct file *file, char __user *buf,
goto out_pages;
}
+ /* Need to re-check in case someone else acquired semaphore */
+ if (!ptrace_may_attach(task)) {
+ ret = -EIO;
+ goto out_pages;
+ }
+
pm.out = (u64 *)buf;
pm.end = (u64 *)(buf + count);
--
1.5.5.1
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