On Fri, Apr 12, 2024 at 10:03:26AM +0800, qiang4.zh...@linux.intel.com wrote:
>From: Qiang Zhang <qiang4.zh...@intel.com>
>
>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 ffff88845dd30000 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-00000000 Dec 28 2023
>[ 9.460789] Call Trace:
>[ 9.463518] <TASK>
>[ 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] </TASK>
>
>[ 9.555649] The buggy address belongs to the physical page:
>[ 9.561875] page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x1
>pfn:0x45dd30
>[ 9.570821] flags: 0x200000000000000(node=0|zone=2)
>[ 9.576271] page_type: 0xffffffff()
>[ 9.580167] raw: 0200000000000000 ffffea0011774c48 ffffea0012ba1848
>0000000000000000
>[ 9.588823] raw: 0000000000000001 0000000000000000 00000000ffffffff
>0000000000000000
>[ 9.597476] page dumped because: kasan: bad access detected
>
>[ 9.605362] Memory state around the buggy address:
>[ 9.610714] ffff88845dd2ff00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>00
>[ 9.618786] ffff88845dd2ff80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>00
>[ 9.626857] >ffff88845dd30000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ff
>[ 9.634930] ^
>[ 9.638534] ffff88845dd30080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ff
>[ 9.646605] ffff88845dd30100: 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 <qiang4.zh...@intel.com>
>---
> 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
>
