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 >