diff options
| author | yonghua zheng <younghua.zheng@gmail.com> | 2013-08-13 16:01:03 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-08-20 08:26:27 -0700 |
| commit | d77d52563beaa75183580949cdce4330a2c6c84d (patch) | |
| tree | 45e02654a9a7d8a81e4fdc3fdfad7ae410480374 | |
| parent | 2e42d79b7e06a080d55da0b05c823c0ba2abaa0c (diff) | |
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.c | 8 |
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; |