Re: [PATCH v2] acpi: nfit: vmalloc-out-of-bounds Read in acpi_nfit_ctl

[Suraj Sonawane <surajsonawane0215@gmail.com>]

On 13/11/24 10:21, Alison Schofield wrote:
> On Tue, Nov 12, 2024 at 10:50:35AM +0530, Suraj Sonawane wrote:
>> Fix an issue detected by syzbot with KASAN:
>>
>> BUG: KASAN: vmalloc-out-of-bounds in cmd_to_func drivers/acpi/nfit/
>> core.c:416 [inline]
>> BUG: KASAN: vmalloc-out-of-bounds in acpi_nfit_ctl+0x20e8/0x24a0
>> drivers/acpi/nfit/core.c:459
>>
>> The issue occurs in `cmd_to_func` when the `call_pkg->nd_reserved2`
>> array is accessed without verifying that `call_pkg` points to a
>> buffer that is sized appropriately as a `struct nd_cmd_pkg`. This
>> could lead to out-of-bounds access and undefined behavior if the
>> buffer does not have sufficient space.
>>
>> To address this issue, a check was added in `acpi_nfit_ctl()` to
>> ensure that `buf` is not `NULL` and `buf_len` is greater than or
>> equal to `sizeof(struct nd_cmd_pkg)` before casting `buf` to
>> `struct nd_cmd_pkg *`. This ensures safe access to the members of
>> `call_pkg`, including the `nd_reserved2` array.
>>
>> This change preventing out-of-bounds reads.
>>
>> Reported-by: syzbot+7534f060ebda6b8b51b3@syzkaller.appspotmail.com
>> Closes: https://syzkaller.appspot.com/bug?extid=7534f060ebda6b8b51b3
>> Tested-by: syzbot+7534f060ebda6b8b51b3@syzkaller.appspotmail.com
>> Fixes: 2d5404caa8c7 ("Linux 6.12-rc7")
>> Signed-off-by: Suraj Sonawane <surajsonawane0215@gmail.com>
> 
> Suraj,
> 
> The fixes tag needs to be where the issue originated, not
> where you discovered it (which I'm guessing was using 6.12-rc7).
> 
Thank you for your feedback.

> Here's how I find the tag:
> 
> $ git blame drivers/acpi/nfit/core.c | grep call_pkg | grep buf
> ebe9f6f19d80d drivers/acpi/nfit/core.c (Dan Williams       2019-02-07 14:56:50 -0800  458) 		call_pkg = buf;
> 
> $ git log -1 --pretty=fixes ebe9f6f19d80d

Thank you for this detailed explaination.
> Fixes: ebe9f6f19d80 ("acpi/nfit: Fix bus command validation")
> 
> I think ^ should be your Fixes tag.

Yes, I ran the provided steps to verify the commit ID ebe9f6f19d80d and 
verified it.
> 
> 
> snip
> 
>>

I'll update the Fixes tag in the next version of the patch. 
Additionally, I will re-test with syzbot and submit the revised patch 
shortly.

Thank you for your time and feedback!

Best,
Suraj Sonawane