From: Nick Piggin Date: Tue, 6 Mar 2007 10:34:25 +0000 (-0800) Subject: [IA64] permon use-after-free fix X-Git-Tag: v2.6.21-rc3~14^2~1 X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=41d5e5d73ecef4ef56b7b4cde962929a712689b4;p=linux-2.6-omap-h63xx.git [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 Cc: Stephane Eranian Signed-off-by: Andrew Morton Signed-off-by: Tony Luck --- diff --git a/arch/ia64/kernel/perfmon.c b/arch/ia64/kernel/perfmon.c index 9ddf896a137..abc7ad03588 100644 --- a/arch/ia64/kernel/perfmon.c +++ b/arch/ia64/kernel/perfmon.c @@ -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; }