Messages in this thread | | | Date | Fri, 18 Aug 2023 12:09:29 -0500 | From | Rob Herring <> | Subject | Re: [PATCH] mm,ima,kexec,of: use memblock_free_late from ima_free_kexec_buffer |
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On Thu, Aug 17, 2023 at 01:57:59PM -0400, Rik van Riel wrote: > The code calling ima_free_kexec_buffer runs long after the memblock > allocator has already been torn down, potentially resulting in a use > after free in memblock_isolate_range. > > With KASAN or KFENCE, this use after free will result in a BUG > from the idle task, and a subsequent kernel panic. > > Switch ima_free_kexec_buffer over to memblock_free_late to avoid > that issue. > > Fixes: fee3ff99bc67 ("powerpc: Move arch independent ima kexec functions to > drivers/of/kexec.c")
Didn't powerpc have the same issue before this commit? The move changed memblock_free() to memblock_phys_free(), but otherwise the code was the same. But wait, the old code looks broken as it reads a phys addr from DT and passes that to memblock_free() which wants a virt addr. Probably should have fixed that before moving things. I guess the Fixes here is right and powerpc needs a different backport for before commit fee3ff99bc67 if they care.
> Cc: stable@kernel.org > Signed-off-by: Rik van Riel <riel@surriel.com> > Suggested-by: Mike Rappoport <rppt@kernel.org> > --- > drivers/of/kexec.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/of/kexec.c b/drivers/of/kexec.c > index f26d2ba8a371..68278340cecf 100644 > --- a/drivers/of/kexec.c > +++ b/drivers/of/kexec.c > @@ -184,7 +184,8 @@ int __init ima_free_kexec_buffer(void) > if (ret) > return ret; > > - return memblock_phys_free(addr, size); > + memblock_free_late(addr, size); > + return 0; > } > #endif > > -- > 2.41.0 >
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