From: Vincent Whitchurch vincent.whitchurch@axis.com
commit 2a4a62a14be1947fa945c5c11ebf67326381a568 upstream.
syscall_stub_data() expects the data_count parameter to be the number of longs, not bytes.
================================================================== BUG: KASAN: stack-out-of-bounds in syscall_stub_data+0x70/0xe0 Read of size 128 at addr 000000006411f6f0 by task swapper/1
CPU: 0 PID: 1 Comm: swapper Not tainted 5.18.0+ #18 Call Trace: show_stack.cold+0x166/0x2a7 __dump_stack+0x3a/0x43 dump_stack_lvl+0x1f/0x27 print_report.cold+0xdb/0xf81 kasan_report+0x119/0x1f0 kasan_check_range+0x3a3/0x440 memcpy+0x52/0x140 syscall_stub_data+0x70/0xe0 write_ldt_entry+0xac/0x190 init_new_ldt+0x515/0x960 init_new_context+0x2c4/0x4d0 mm_init.constprop.0+0x5ed/0x760 mm_alloc+0x118/0x170 0x60033f48 do_one_initcall+0x1d7/0x860 0x60003e7b kernel_init+0x6e/0x3d4 new_thread_handler+0x1e7/0x2c0
The buggy address belongs to stack of task swapper/1 and is located at offset 64 in frame: init_new_ldt+0x0/0x960
This frame has 2 objects: [32, 40) 'addr' [64, 80) 'desc' ==================================================================
Fixes: 858259cf7d1c443c83 ("uml: maintain own LDT entries") Signed-off-by: Vincent Whitchurch vincent.whitchurch@axis.com Cc: stable@vger.kernel.org Signed-off-by: Richard Weinberger richard@nod.at Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/um/ldt.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
--- a/arch/x86/um/ldt.c +++ b/arch/x86/um/ldt.c @@ -23,9 +23,11 @@ static long write_ldt_entry(struct mm_id { long res; void *stub_addr; + + BUILD_BUG_ON(sizeof(*desc) % sizeof(long)); + res = syscall_stub_data(mm_idp, (unsigned long *)desc, - (sizeof(*desc) + sizeof(long) - 1) & - ~(sizeof(long) - 1), + sizeof(*desc) / sizeof(long), addr, &stub_addr); if (!res) { unsigned long args[] = { func,