3.2.51-rc1 review patch. If anyone has any objections, please let me know.
------------------ From: yonghua zheng <younghua.zh...@gmail.com> 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. [a...@linux-foundation.org: document pagemapread.pos and .len units, fix PM_ENTRY_BYTES definition] Signed-off-by: Yonghua Zheng <younghua.zh...@gmail.com> Signed-off-by: Andrew Morton <a...@linux-foundation.org> Signed-off-by: Linus Torvalds <torva...@linux-foundation.org> [bwh: Backported to 3.2: - Adjust context - There is no pagemap_entry_t definition; keep using u64] Signed-off-by: Ben Hutchings <b...@decadent.org.uk> --- fs/proc/task_mmu.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -604,7 +604,7 @@ const struct file_operations proc_clear_ }; struct pagemapread { - int pos, len; + int pos, len; /* units: PM_ENTRY_BYTES, not bytes */ u64 *buffer; }; @@ -792,8 +792,8 @@ static ssize_t pagemap_read(struct file 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; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/