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| author | yonghua zheng <younghua.zheng@gmail.com> | 2013-08-14 03:01:03 +0400 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-08-14 04:57:50 +0400 |
| commit | 8c8296223f3abb142be8fc31711b18a704c0e7d8 (patch) | |
| tree | 1de036ad6669fc8c4b9ce45eea00d514e4261944 /fs | |
| parent | 57a1a1976318beb8de0e544039072a4fe1afa37c (diff) | |
| download | linux-8c8296223f3abb142be8fc31711b18a704c0e7d8.tar.xz | |
fs/proc/task_mmu.c: fix buffer overflow in add_page_map()
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>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs')
| -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 a11720767abc..107d026f5d6e 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -868,7 +868,7 @@ typedef struct { } pagemap_entry_t; struct pagemapread { - int pos, len; + int pos, len; /* units: PM_ENTRY_BYTES, not bytes */ pagemap_entry_t *buffer; bool v2; }; @@ -876,7 +876,7 @@ struct pagemapread { #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) @@ -1127,8 +1127,8 @@ static ssize_t pagemap_read(struct file *file, char __user *buf, goto out_task; pm.v2 = soft_dirty_cleared; - 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; |