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Subject[PATCH v2] of: fix kmemleak crash (was: Re: kmemleak panic)
On Wed, Jan 23, 2019 at 08:28:03AM +0100, Marek Szyprowski wrote:
> Hi Mike,
>
> On 2019-01-23 06:54, Mike Rapoport wrote:
>
> > @@ -37,21 +37,16 @@ int __init __weak early_init_dt_alloc_reserved_memory_arch(phys_addr_t size,
> > */
> > end = !end ? MEMBLOCK_ALLOC_ANYWHERE : end;
> > align = !align ? SMP_CACHE_BYTES : align;
> > - base = __memblock_alloc_base(size, align, end);
> > + base = memblock_find_in_range(size, align, start, end);
>
> Please remove a comment about __memblock_alloc_base() above that block
> of code. It is no longer needed after this change.

Huh, missed that, thanks!
Fixed now.

From 2f340afcc8cc81f1829a19f9c595a9995656e547 Mon Sep 17 00:00:00 2001
From: Mike Rapoport <rppt@linux.ibm.com>
Date: Wed, 23 Jan 2019 07:38:50 +0200
Subject: [PATCH v2] of: fix kmemleak crash caused by imbalance in early memory
reservation

Marc Gonzalez reported the following kmemleak crash:

Unable to handle kernel paging request at virtual address ffffffc021e00000
Mem abort info:
ESR = 0x96000006
Exception class = DABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
Data abort info:
ISV = 0, ISS = 0x00000006
CM = 0, WnR = 0
swapper pgtable: 4k pages, 39-bit VAs, pgdp = (____ptrval____)
[ffffffc021e00000] pgd=000000017e3ba803, pud=000000017e3ba803,
pmd=0000000000000000
Internal error: Oops: 96000006 [#1] PREEMPT SMP
Modules linked in:
CPU: 6 PID: 523 Comm: kmemleak Tainted: G S W 5.0.0-rc1 #13
Hardware name: Qualcomm Technologies, Inc. MSM8998 v1 MTP (DT)
pstate: 80000085 (Nzcv daIf -PAN -UAO)
pc : scan_block+0x70/0x190
lr : scan_block+0x6c/0x190
sp : ffffff8012e8bd20
x29: ffffff8012e8bd20 x28: ffffffc0fdbaf018
x27: ffffffc022000000 x26: 0000000000000080
x25: ffffff8011aadf70 x24: ffffffc0f8cc8000
x23: ffffff8010dc8000 x22: ffffff8010dc8830
x21: ffffffc021e00ff9 x20: ffffffc0f8cc8050
x19: ffffffc021e00000 x18: 0000000000002409
x17: 0000000000000200 x16: 0000000000000000
x15: ffffff8010e14dd8 x14: 0000000000002406
x13: 000000004c4dd0c6 x12: ffffffc0f77dad58
x11: 0000000000000001 x10: ffffff8010d9e688
x9 : ffffff8010d9f000 x8 : ffffff8010d9e688
x7 : 0000000000000002 x6 : 0000000000000000
x5 : ffffff8011511c20 x4 : 00000000000026d1
x3 : ffffff8010e14d88 x2 : 5b36396f4e7d4000
x1 : 0000000000208040 x0 : 0000000000000000
Process kmemleak (pid: 523, stack limit = 0x(____ptrval____))
Call trace:
scan_block+0x70/0x190
scan_gray_list+0x108/0x1c0
kmemleak_scan+0x33c/0x7c0
kmemleak_scan_thread+0x98/0xf0
kthread+0x11c/0x120
ret_from_fork+0x10/0x1c
Code: f9000fb4 d503201f 97ffffd2 35000580 (f9400260)
---[ end trace 176d6ed9d86a0c33 ]---
note: kmemleak[523] exited with preempt_count 2

The crash happens when a no-map area is allocated in
early_init_dt_alloc_reserved_memory_arch(). The allocated region is
registered with kmemleak, but it is then removed from memblock using
memblock_remove() that is not kmemleak-aware.

Replacing __memblock_alloc_base() with memblock_find_in_range() makes sure
that the allocated memory is not added to kmemleak and then
memblock_remove()'ing this memory is safe.

As a bonus, since memblock_find_in_range() ensures the allocation in the
specified range, the bounds check can be removed.

Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Tested-by: Marc Gonzalez <marc.w.gonzalez@free.fr>
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
---
drivers/of/of_reserved_mem.c | 18 +++++-------------
1 file changed, 5 insertions(+), 13 deletions(-)

diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c
index 1977ee0adcb1..2ae81604ffef 100644
--- a/drivers/of/of_reserved_mem.c
+++ b/drivers/of/of_reserved_mem.c
@@ -31,27 +31,19 @@ int __init __weak early_init_dt_alloc_reserved_memory_arch(phys_addr_t size,
phys_addr_t *res_base)
{
phys_addr_t base;
- /*
- * We use __memblock_alloc_base() because memblock_alloc_base()
- * panic()s on allocation failure.
- */
+
end = !end ? MEMBLOCK_ALLOC_ANYWHERE : end;
align = !align ? SMP_CACHE_BYTES : align;
- base = __memblock_alloc_base(size, align, end);
+ base = memblock_find_in_range(size, align, start, end);
if (!base)
return -ENOMEM;

- /*
- * Check if the allocated region fits in to start..end window
- */
- if (base < start) {
- memblock_free(base, size);
- return -ENOMEM;
- }
-
*res_base = base;
if (nomap)
return memblock_remove(base, size);
+ else
+ return memblock_reserve(base, size);
+
return 0;
}

--
2.7.4


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