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authoryonghua zheng <younghua.zheng@gmail.com>2013-08-13 16:01:03 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-08-20 08:26:27 -0700
commitd77d52563beaa75183580949cdce4330a2c6c84d (patch)
tree45e02654a9a7d8a81e4fdc3fdfad7ae410480374
parent2e42d79b7e06a080d55da0b05c823c0ba2abaa0c (diff)
downloadlinux-linaro-stable-d77d52563beaa75183580949cdce4330a2c6c84d.tar.gz
fs/proc/task_mmu.c: fix buffer overflow in add_page_map()
commit 8c8296223f3abb142be8fc31711b18a704c0e7d8 upstream. Recently we met quite a lot of random kernel panic issues after enabling CONFIG_PROC_PAGE_MONITOR. After debuggind we found this has something to do with following bug in pagemap: In struct pagemapread: struct pagemapread { int pos, len; pagemap_entry_t *buffer; bool v2; }; pos is number of PM_ENTRY_BYTES in buffer, but len is the size of buffer, it is a mistake to compare pos and len in add_page_map() for checking buffer is full or not, and this can lead to buffer overflow and random kernel panic issue. Correct len to be total number of PM_ENTRY_BYTES in buffer. [akpm@linux-foundation.org: document pagemapread.pos and .len units, fix PM_ENTRY_BYTES definition] Signed-off-by: Yonghua Zheng <younghua.zheng@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--fs/proc/task_mmu.c8
1 files changed, 4 insertions, 4 deletions
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 7faaf2acc570..8df7fd28cca7 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -679,14 +679,14 @@ typedef struct {
} pagemap_entry_t;
struct pagemapread {
- int pos, len;
+ int pos, len; /* units: PM_ENTRY_BYTES, not bytes */
pagemap_entry_t *buffer;
};
#define PAGEMAP_WALK_SIZE (PMD_SIZE)
#define PAGEMAP_WALK_MASK (PMD_MASK)
-#define PM_ENTRY_BYTES sizeof(u64)
+#define PM_ENTRY_BYTES sizeof(pagemap_entry_t)
#define PM_STATUS_BITS 3
#define PM_STATUS_OFFSET (64 - PM_STATUS_BITS)
#define PM_STATUS_MASK (((1LL << PM_STATUS_BITS) - 1) << PM_STATUS_OFFSET)
@@ -913,8 +913,8 @@ static ssize_t pagemap_read(struct file *file, char __user *buf,
if (!count)
goto out_task;
- pm.len = PM_ENTRY_BYTES * (PAGEMAP_WALK_SIZE >> PAGE_SHIFT);
- pm.buffer = kmalloc(pm.len, GFP_TEMPORARY);
+ pm.len = (PAGEMAP_WALK_SIZE >> PAGE_SHIFT);
+ pm.buffer = kmalloc(pm.len * PM_ENTRY_BYTES, GFP_TEMPORARY);
ret = -ENOMEM;
if (!pm.buffer)
goto out_task;