From: Nick Piggin 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 Cc: Stephane Eranian Cc: "Luck, Tony" Signed-off-by: Andrew Morton --- arch/ia64/kernel/perfmon.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff -puN arch/ia64/kernel/perfmon.c~ia64-permon-use-after-free-fix arch/ia64/kernel/perfmon.c --- a/arch/ia64/kernel/perfmon.c~ia64-permon-use-after-free-fix +++ a/arch/ia64/kernel/perfmon.c @@ -2299,7 +2299,7 @@ pfm_remap_buffer(struct vm_area_struct * * 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 * 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 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, } 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 /* * 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, v * 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; } _