apfs/linux-apfs
0
0
Fork 0
mirror of https://github.com/linux-apfs/linux-apfs.git synced 2026-05-01 15:00:59 -07:00
Code Issues Packages Projects Releases Wiki Activity

powerpc: Fix null pointer deref in perf hardware breakpoints

Browse Source 
Currently if you are doing a global perf recording with hardware
breakpoints (ie perf record -e mem:0xdeadbeef -a), you can oops with:

  Faulting instruction address: 0xc000000000738890
  cpu 0xc: Vector: 300 (Data Access) at [c0000003f76af8d0]
      pc: c000000000738890: .hw_breakpoint_handler+0xa0/0x1e0
      lr: c000000000738830: .hw_breakpoint_handler+0x40/0x1e0
      sp: c0000003f76afb50
     msr: 8000000000001032
     dar: 6f0
   dsisr: 42000000
    current = 0xc0000003f765ac00
    paca    = 0xc00000000f262a00   softe: 0        irq_happened: 0x01
    pid   = 6810, comm = loop-read
  enter ? for help
  [c0000003f76afbe0] c00000000073cd04 .notifier_call_chain.isra.0+0x84/0xe0
  [c0000003f76afc80] c00000000073cdbc .notify_die+0x3c/0x60
  [c0000003f76afd20] c0000000000139f0 .do_dabr+0x40/0xf0
  [c0000003f76afe30] c000000000005a9c handle_dabr_fault+0x14/0x48
  --- Exception: 300 (Data Access) at 0000000010000480
  SP (ff8679e0) is in userspace

This is because we don't check to see if the break point is associated
with task before we deference the task_struct pointer.

This changes the update to use current.

Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Michael Neuling
2012-08-22 20:30:43 +00:00
committed by Benjamin Herrenschmidt
parent e3bc8049e5
commit 6d9c00c67b
1 changed files with 1 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files
arch/powerpc/kernel/hw_breakpoint.c
+1 -1
View File
@@ -253,7 +253,7 @@ int __kprobes hw_breakpoint_handler(struct die_args *args)
/* Do not emulate user-space instructions, instead single-step them */
if (user_mode(regs)) {
bp->ctx->task->thread.last_hit_ubp = bp;
current->thread.last_hit_ubp = bp;
regs->msr |= MSR_SE;
goto out;
}