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Commit 41d5e5d7 authored by Nick Piggin's avatar Nick Piggin Committed by Tony Luck
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[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: default avatarNick Piggin <npiggin@suse.de>
Cc: Stephane Eranian <eranian@hpl.hp.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarTony Luck <tony.luck@intel.com>
parent 50157b09

arch/ia64/kernel/perfmon.c

+7 −4
Original line number Diff line number Diff line
@@ -2299,7 +2299,7 @@ pfm_remap_buffer(struct vm_area_struct *vma, unsigned long buf, unsigned long ad 
 * 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 @@ pfm_smpl_buffer_alloc(struct task_struct *task, pfm_context_t *ctx, unsigned lon 
	 * 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 @@ pfm_smpl_buffer_alloc(struct task_struct *task, pfm_context_t *ctx, unsigned lon 
		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 @@ pfarg_is_sane(struct task_struct *task, pfarg_context_t *pfx) 
}



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 @@ pfm_setup_buffer_fmt(struct task_struct *task, pfm_context_t *ctx, unsigned int 
		/*

		 * 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 @@ pfm_context_create(pfm_context_t *ctx, void *arg, int count, struct pt_regs *reg 
	 * 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;

	}