[IA64] permon use-after-free fix
Perfmon associates vmalloc()ed memory with a file descriptor, and installs
a vma mapping that memory. Unfortunately, the vm_file field is not filled
in, so processes with mappings to that memory do not prevent the file from
being closed and the memory freed. This results in use-after-free bugs and
multiple freeing of pages, etc.
I saw this bug on an Altix on SLES9. Haven't reproduced upstream but it
looks like the same issue is there.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Stephane Eranian <eranian@hpl.hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>
diff --git a/arch/ia64/kernel/perfmon.c b/arch/ia64/kernel/perfmon.c
index 9ddf896..abc7ad0 100644
--- a/arch/ia64/kernel/perfmon.c
+++ b/arch/ia64/kernel/perfmon.c
@@ -2299,7 +2299,7 @@
* allocate a sampling buffer and remaps it into the user address space of the task
*/
static int
-pfm_smpl_buffer_alloc(struct task_struct *task, pfm_context_t *ctx, unsigned long rsize, void **user_vaddr)
+pfm_smpl_buffer_alloc(struct task_struct *task, struct file *filp, pfm_context_t *ctx, unsigned long rsize, void **user_vaddr)
{
struct mm_struct *mm = task->mm;
struct vm_area_struct *vma = NULL;
@@ -2349,6 +2349,7 @@
* partially initialize the vma for the sampling buffer
*/
vma->vm_mm = mm;
+ vma->vm_file = filp;
vma->vm_flags = VM_READ| VM_MAYREAD |VM_RESERVED;
vma->vm_page_prot = PAGE_READONLY; /* XXX may need to change */
@@ -2387,6 +2388,8 @@
goto error;
}
+ get_file(filp);
+
/*
* now insert the vma in the vm list for the process, must be
* done with mmap lock held
@@ -2464,7 +2467,7 @@
}
static int
-pfm_setup_buffer_fmt(struct task_struct *task, pfm_context_t *ctx, unsigned int ctx_flags,
+pfm_setup_buffer_fmt(struct task_struct *task, struct file *filp, pfm_context_t *ctx, unsigned int ctx_flags,
unsigned int cpu, pfarg_context_t *arg)
{
pfm_buffer_fmt_t *fmt = NULL;
@@ -2505,7 +2508,7 @@
/*
* buffer is always remapped into the caller's address space
*/
- ret = pfm_smpl_buffer_alloc(current, ctx, size, &uaddr);
+ ret = pfm_smpl_buffer_alloc(current, filp, ctx, size, &uaddr);
if (ret) goto error;
/* keep track of user address of buffer */
@@ -2716,7 +2719,7 @@
* does the user want to sample?
*/
if (pfm_uuid_cmp(req->ctx_smpl_buf_id, pfm_null_uuid)) {
- ret = pfm_setup_buffer_fmt(current, ctx, ctx_flags, 0, req);
+ ret = pfm_setup_buffer_fmt(current, filp, ctx, ctx_flags, 0, req);
if (ret) goto buffer_error;
}