Re: [PATCH] bootconfig: use memblock_free_late to free xbc memory to buddy
On Fri, Apr 12, 2024 at 10:03:26AM +0800, qiang4.zh...@linux.intel.com wrote:
>From: Qiang Zhang
>
>On the time to free xbc memory, memblock has handed over memory to buddy
>allocator. So it doesn't make sense to free memory back to memblock.
>memblock_free() called by xbc_exit() even causes UAF bugs on architectures
>with CONFIG_ARCH_KEEP_MEMBLOCK disabled like x86. Following KASAN logs
>shows this case.
>
>[9.410890]
>==
>[9.418962] BUG: KASAN: use-after-free in memblock_isolate_range+0x12d/0x260
>[9.426850] Read of size 8 at addr 88845dd3 by task swapper/0/1
>
>[9.435901] CPU: 9 PID: 1 Comm: swapper/0 Tainted: G U
>6.9.0-rc3-00208-g586b5dfb51b9 #5
>[9.446403] Hardware name: Intel Corporation RPLP LP5 (CPU:RaptorLake)/RPLP
>LP5 (ID:13), BIOS IRPPN02.01.01.00.00.19.015.D- Dec 28 2023
>[9.460789] Call Trace:
>[9.463518]
>[9.465859] dump_stack_lvl+0x53/0x70
>[9.469949] print_report+0xce/0x610
>[9.473944] ? __virt_addr_valid+0xf5/0x1b0
>[9.478619] ? memblock_isolate_range+0x12d/0x260
>[9.483877] kasan_report+0xc6/0x100
>[9.487870] ? memblock_isolate_range+0x12d/0x260
>[9.493125] memblock_isolate_range+0x12d/0x260
>[9.498187] memblock_phys_free+0xb4/0x160
>[9.502762] ? __pfx_memblock_phys_free+0x10/0x10
>[9.508021] ? mutex_unlock+0x7e/0xd0
>[9.512111] ? __pfx_mutex_unlock+0x10/0x10
>[9.516786] ? kernel_init_freeable+0x2d4/0x430
>[9.521850] ? __pfx_kernel_init+0x10/0x10
>[9.526426] xbc_exit+0x17/0x70
>[9.529935] kernel_init+0x38/0x1e0
>[9.533829] ? _raw_spin_unlock_irq+0xd/0x30
>[9.538601] ret_from_fork+0x2c/0x50
>[9.542596] ? __pfx_kernel_init+0x10/0x10
>[9.547170] ret_from_fork_asm+0x1a/0x30
>[9.551552]
>
>[9.555649] The buggy address belongs to the physical page:
>[9.561875] page: refcount:0 mapcount:0 mapping: index:0x1
>pfn:0x45dd30
>[9.570821] flags: 0x200(node=0|zone=2)
>[9.576271] page_type: 0x()
>[9.580167] raw: 0200 ea0011774c48 ea0012ba1848
>
>[9.588823] raw: 0001
>
>[9.597476] page dumped because: kasan: bad access detected
>
>[9.605362] Memory state around the buggy address:
>[9.610714] 88845dd2ff00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>00
>[9.618786] 88845dd2ff80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>00
>[9.626857] >88845dd3: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ff
>[9.634930]^
>[9.638534] 88845dd30080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ff
>[9.646605] 88845dd30100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ff
>[9.654675]
>==
Sorry. Forget to Cc stable. Will send a new one.
>
>Signed-off-by: Qiang Zhang
>---
> lib/bootconfig.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
>diff --git a/lib/bootconfig.c b/lib/bootconfig.c
>index c59d26068a64..4524ee944df0 100644
>--- a/lib/bootconfig.c
>+++ b/lib/bootconfig.c
>@@ -63,7 +63,7 @@ static inline void * __init xbc_alloc_mem(size_t size)
>
> static inline void __init xbc_free_mem(void *addr, size_t size)
> {
>- memblock_free(addr, size);
>+ memblock_free_late(__pa(addr), size);
> }
>
> #else /* !__KERNEL__ */
>--
>2.39.2
>
[PATCH] bootconfig: use memblock_free_late to free xbc memory to buddy
From: Qiang Zhang
On the time to free xbc memory, memblock has handed over memory to buddy
allocator. So it doesn't make sense to free memory back to memblock.
memblock_free() called by xbc_exit() even causes UAF bugs on architectures
with CONFIG_ARCH_KEEP_MEMBLOCK disabled like x86. Following KASAN logs
shows this case.
[9.410890]
==
[9.418962] BUG: KASAN: use-after-free in memblock_isolate_range+0x12d/0x260
[9.426850] Read of size 8 at addr 88845dd3 by task swapper/0/1
[9.435901] CPU: 9 PID: 1 Comm: swapper/0 Tainted: G U
6.9.0-rc3-00208-g586b5dfb51b9 #5
[9.446403] Hardware name: Intel Corporation RPLP LP5 (CPU:RaptorLake)/RPLP
LP5 (ID:13), BIOS IRPPN02.01.01.00.00.19.015.D- Dec 28 2023
[9.460789] Call Trace:
[9.463518]
[9.465859] dump_stack_lvl+0x53/0x70
[9.469949] print_report+0xce/0x610
[9.473944] ? __virt_addr_valid+0xf5/0x1b0
[9.478619] ? memblock_isolate_range+0x12d/0x260
[9.483877] kasan_report+0xc6/0x100
[9.487870] ? memblock_isolate_range+0x12d/0x260
[9.493125] memblock_isolate_range+0x12d/0x260
[9.498187] memblock_phys_free+0xb4/0x160
[9.502762] ? __pfx_memblock_phys_free+0x10/0x10
[9.508021] ? mutex_unlock+0x7e/0xd0
[9.512111] ? __pfx_mutex_unlock+0x10/0x10
[9.516786] ? kernel_init_freeable+0x2d4/0x430
[9.521850] ? __pfx_kernel_init+0x10/0x10
[9.526426] xbc_exit+0x17/0x70
[9.529935] kernel_init+0x38/0x1e0
[9.533829] ? _raw_spin_unlock_irq+0xd/0x30
[9.538601] ret_from_fork+0x2c/0x50
[9.542596] ? __pfx_kernel_init+0x10/0x10
[9.547170] ret_from_fork_asm+0x1a/0x30
[9.551552]
[9.555649] The buggy address belongs to the physical page:
[9.561875] page: refcount:0 mapcount:0 mapping: index:0x1
pfn:0x45dd30
[9.570821] flags: 0x200(node=0|zone=2)
[9.576271] page_type: 0x()
[9.580167] raw: 0200 ea0011774c48 ea0012ba1848
[9.588823] raw: 0001
[9.597476] page dumped because: kasan: bad access detected
[9.605362] Memory state around the buggy address:
[9.610714] 88845dd2ff00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00
[9.618786] 88845dd2ff80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00
[9.626857] >88845dd3: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ff
[9.634930]^
[9.638534] 88845dd30080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ff
[9.646605] 88845dd30100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ff
[9.654675]
==
Signed-off-by: Qiang Zhang
---
lib/bootconfig.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/lib/bootconfig.c b/lib/bootconfig.c
index c59d26068a64..4524ee944df0 100644
--- a/lib/bootconfig.c
+++ b/lib/bootconfig.c
@@ -63,7 +63,7 @@ static inline void * __init xbc_alloc_mem(size_t size)
static inline void __init xbc_free_mem(void *addr, size_t size)
{
- memblock_free(addr, size);
+ memblock_free_late(__pa(addr), size);
}
#else /* !__KERNEL__ */
--
2.39.2
