Messages in this thread Patch in this message | | | Date | Mon, 08 Jun 2009 12:16:57 -0500 | From | steiner@sgi ... | Subject | [Patch 09/12] GRU - fix potential use-after-free when purging GRU tlbs |
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From: Jack Steiner <steiner@sgi.com>
Fix potential SGI GRU bug that could cause a use-after-free. If one thread in a task is flushing the GRU and another thread destroys the GRU context, there is the potential to access a table after it has been freed.
Copy the gms pointer to a local variable before unlocking the gts table. Note that no refcnt is needed for the gms - the reference is held indirectly by the task's mm_struct.
Signed-off-by: Jack Steiner <steiner@sgi.com>
--- drivers/misc/sgi-gru/grufault.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
Index: linux/drivers/misc/sgi-gru/grufault.c =================================================================== --- linux.orig/drivers/misc/sgi-gru/grufault.c 2009-06-05 15:33:05.000000000 -0500 +++ linux/drivers/misc/sgi-gru/grufault.c 2009-06-05 15:33:05.000000000 -0500 @@ -706,6 +706,7 @@ int gru_user_flush_tlb(unsigned long arg { struct gru_thread_state *gts; struct gru_flush_tlb_req req; + struct gru_mm_struct *gms; STAT(user_flush_tlb); if (copy_from_user(&req, (void __user *)arg, sizeof(req))) @@ -718,8 +719,9 @@ int gru_user_flush_tlb(unsigned long arg if (!gts) return -EINVAL; - gru_flush_tlb_range(gts->ts_gms, req.vaddr, req.len); + gms = gts->ts_gms; gru_unlock_gts(gts); + gru_flush_tlb_range(gms, req.vaddr, req.len); return 0; }
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