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* Re: [PATCH v4 2/3] RAS: Fix out-of-bounds read when tracing arm_event
@ 2026-09-21  1:27 Liuwenliang (Abbott Liu)
  0 siblings, 0 replies; 3+ messages in thread
From: Liuwenliang (Abbott Liu) @ 2026-09-21  1:27 UTC (permalink / raw)
  To: Guohanjun (Hanjun Guo),
	tony.luck, bp, ardb, mchehab+huawei, rafael.j.wysocki, jic23,
	jason, danielf, luoshengwei, linux-edac, linux-kernel
  Cc: yangzhuohao (A),
	douzhaolei, zouyipeng, Wangbing, Nixiaoming,
	ACPI Devel Maling List, Liuwenliang (Abbott Liu)

Hi Hanjun,

Thank you for the review.

On 2026/9/17 10:14, Hanjun Guo wrote:
> On 2026/9/9 19:28, Abbott Liu wrote:
> > The vsei_len < 0 error path did not verify the pei_len and ctx_len.
> > When vsei_len is negative, section_length is too small to hold the
> > full record, yet pei_len and ctx_len were derived from
> > err_info_num/context_info_num and may describe regions beyond the
> > (long)err .. err + section_length buffer. To prevent trace_arm_event
> > from reading past the allocated record, sanitize the parameters:
> > recalculate ctx_len and pei_len based on section_length, limit them,
> > and set the corresponding pointers to NULL and lengths to 0 when
> > there is no remaining space.
> >
> > pei_len and ctx_len become s32 so that the recalculated lengths can
> > be checked for negative values.
> >
> > Fixes: 05954511b73e ("RAS: Report all ARM processor CPER information to userspace")
> > Signed-off-by: Abbott Liu <liuwenliang@huawei.com>
> > ---
> >   drivers/ras/ras.c | 22 ++++++++++++++++++----
> >   1 file changed, 18 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/ras/ras.c b/drivers/ras/ras.c
> > index 2540538a16a8..085fe2d980e5 100644
> > --- a/drivers/ras/ras.c
> > +++ b/drivers/ras/ras.c
> > @@ -58,10 +58,10 @@ void log_arm_hw_error(struct cper_sec_proc_arm *err, const u8 sev)
> >   	struct cper_arm_err_info *err_info;
> >   	struct cper_arm_ctx_info *ctx_info;
> >   	u8 *ven_err_data;
> > -	u32 ctx_len = 0;
> > +	s32 ctx_len = 0;
> >   	int n, sz, cpu;
> >   	s32 vsei_len;
> > -	u32 pei_len;
> > +	s32 pei_len;
> >   	u8 *pei_err, *ctx_err;
> >
> >   	pei_len = sizeof(struct cper_arm_err_info) * err->err_info_num;
> > @@ -87,14 +87,28 @@ void log_arm_hw_error(struct cper_sec_proc_arm *err, const u8 sev)
> >   		pr_warn(FW_BUG "section length is too small\n");
> >   		pr_warn(FW_BUG "firmware-generated error record is incorrect\n");
> >   		vsei_len = 0;
> > +		ven_err_data = NULL;
> > +
> > +		ctx_len = err->section_length - (sizeof(struct cper_sec_proc_arm) + pei_len);
> > +		if (ctx_len < 0) {
> > +			ctx_len = 0;
> > +			ctx_err = NULL;
> > +
> > +			pei_len = err->section_length - sizeof(struct cper_sec_proc_arm);
> > +			if (pei_len < 0) {
> > +				pei_len = 0;
> > +				pei_err = NULL;
> > +			}
> > +		}
> > +	} else {
> > +		ven_err_data = (u8 *)ctx_info;
> >   	}
> > -	ven_err_data = (u8 *)ctx_info;
> >
> >   	cpu = GET_LOGICAL_INDEX(err->mpidr);
> >   	if (cpu < 0)
> >   		cpu = -1;
> >
> > -	trace_arm_event(err, pei_err, pei_len, ctx_err, ctx_len,
> > +	trace_arm_event(err, pei_err, (u32)pei_len, ctx_err, (u32)ctx_len,
> >   			ven_err_data, (u32)vsei_len, sev, cpu);
> >   }
>
> Reviewed-by: Hanjun Guo <guohanjun@huawei.com>

Thanks, I will add your Reviewed-by tag in v5, there will be no code changes in
that version, so the tag remains valid.

>
> Thanks
> Hanjun

^ permalink raw reply	[flat|nested] 3+ messages in thread
* [PATCH v4 0/3] RAS: Fix ARM processor error bounds checking
@ 2026-09-09 11:28 Abbott Liu
  2026-09-09 11:28 ` [PATCH v4 2/3] RAS: Fix out-of-bounds read when tracing arm_event Abbott Liu
  0 siblings, 1 reply; 3+ messages in thread
From: Abbott Liu @ 2026-09-09 11:28 UTC (permalink / raw)
  To: tony.luck, bp, ardb, mchehab+huawei, rafael.j.wysocki, guohanjun,
	jic23, jason, danielf, luoshengwei, linux-edac, linux-kernel
  Cc: yangzhuohao1, douzhaolei, zouyipeng, wangbing6, nixiaoming, liuwenliang

Commit 87880af2d24e ("APEI/GHES: ARM processor Error: don't go past
allocated memory") and commit 05954511b73e ("RAS: Report all ARM
processor CPER information to userspace") introduced bounds checking
for malformed ARM processor error records in log_arm_hw_error().
However, three issues remain:

1. The ctx_info bounds check condition is inverted: it adds
   ctx_info->size when the context header is already past the end of
   the section instead of when it is within bounds.

2. When vsei_len < 0, the error path does not verify pei_len and
   ctx_len. Since these are derived from err_info_num and
   context_info_num, they may describe regions beyond the allocated
   record, causing trace_arm_event() to read out of bounds.

3. ctx_info->size is a u32 taken directly from the firmware-generated
   record. A value over 0x7fffffff overflows the signed int sz used
   to advance ctx_info, so the iteration can walk past the end of the
   section.

Patch 1 fixes the inverted bounds check for context info iteration.
Patch 2 sanitizes pei_len/ctx_len/ven_err_data in the vsei_len < 0
error path to prevent out-of-bounds reads in trace_arm_event().
Patch 3 checks each context entry with 64-bit arithmetic so that both
the header and the context data fit in the section, and stops the walk
at the first entry that does not fit, so a malformed size cannot
overflow sz and walk ctx_info out of the section.

Changes in v4:
  - Remove the empty line between the Fixes: and Signed-off-by: tags
    in patches 1 and 2, per Hanjun Guo's comments.
  - Add braces around the else branch that assigns ven_err_data in
    patch 2, as suggested by Hanjun Guo.
  - Add new patch 3 to check each context entry with 64-bit
    arithmetic and stop the walk at the first entry that does not fit
    in the section, so a ctx_info->size over 0x7fffffff cannot
    overflow the signed int sz and walk ctx_info past the section,
    addressing Hanjun Guo's overflow comment.

Changes in v3:
  - There was no change, and the email was sent by mistake.

Changes in v2:
  - Split the original single patch into two separate patches, one
    for each distinct fix, to ease review and backporting.

v2:
  RAS: Fix ARM processor error bounds checking
  https://lore.kernel.org/all/20260825134323.4181892-1-liuwenliang@huawei.com/

v1:
  RAS: Fix out-of-range section_length in ARM processor error handling
  https://lore.kernel.org/all/20260820131829.1006371-1-liuwenliang@huawei.com/

Abbott Liu (3):
  RAS: Fix inverted context info bounds check in ARM processor errors
  RAS: Fix out-of-bounds read when tracing arm_event
  RAS: Fix integer overflow in ARM processor error context walk

 drivers/ras/ras.c | 33 +++++++++++++++++++++++++++------
 1 file changed, 27 insertions(+), 6 deletions(-)

-- 
2.43.0

^ permalink raw reply	[flat|nested] 3+ messages in thread
end of thread, other threads:[~2026-09-21  1:27 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2026-09-21  1:27 [PATCH v4 2/3] RAS: Fix out-of-bounds read when tracing arm_event Liuwenliang (Abbott Liu)
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2026-09-09 11:28 [PATCH v4 0/3] RAS: Fix ARM processor error bounds checking Abbott Liu
2026-09-09 11:28 ` [PATCH v4 2/3] RAS: Fix out-of-bounds read when tracing arm_event Abbott Liu
2026-09-17  2:14   ` Hanjun Guo

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