Re: [Xen-devel] [PATCH for-4.9 v3 3/3] xen/livepatch: Don't crash on encountering STN_UNDEF relocations

[Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>]

On 06/22/2017 07:15 PM, Andrew Cooper wrote:
> A symndx of STN_UNDEF is special, and means a symbol value of 0.  While
> legitimate in the ELF standard, its existance in a livepatch is questionable
> at best.  Until a plausible usecase presents itself, reject such a relocation
> with -EOPNOTSUPP.
>
> Additionally, fix an off-by-one error while range checking symndx, and perform
> a safety check on elf->sym[symndx].sym before derefencing it, to avoid
> tripping over a NULL pointer when calculating val.
>
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Reviewed-by: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>

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