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Re: [PATCH] x86/debug: fix page-overflow bug in dbg_rw_guest_mem


  • To: Tamas K Lengyel <tamas@xxxxxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxxx>
  • From: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
  • Date: Sat, 30 Jan 2021 02:59:45 +0000
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On 30/01/2021 01:59, Tamas K Lengyel wrote:
> When using gdbsx dbg_rw_guest_mem is used to read/write guest memory. When the
> buffer being accessed is on a page-boundary, the next page needs to be grabbed
> to access the correct memory for the buffer's overflown parts. While
> dbg_rw_guest_mem has logic to handle that, it broke with 229492e210a. Instead
> of grabbing the next page the code right now is looping back to the
> start of the first page. This results in errors like the following while 
> trying
> to use gdb with Linux' lx-dmesg:
>
> [    0.114457] PM: hibernation: Registered nosave memory: [mem
> 0xfdfff000-0xffffffff]
> [    0.114460] [mem 0x90000000-0xfbffffff] available for PCI demem 0
> [    0.114462] f]f]
> Python Exception <class 'ValueError'> embedded null character:
> Error occurred in Python: embedded null character
>
> Fixing this bug by taking the variable assignment outside the loop.
>
> Signed-off-by: Tamas K Lengyel <tamas@xxxxxxxxxxxxx>

Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

Sorry for breaking this...



 


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