From 6047980008d8db5de9ef5c7ad897f5d2caac003c Mon Sep 17 00:00:00 2001 From: Vasily Gorbik Date: Wed, 15 Nov 2017 14:15:36 +0100 Subject: [PATCH] s390/disassembler: increase show_code buffer size commit b192571d1ae375e0bbe0aa3ccfa1a3c3704454b9 upstream. Current buffer size of 64 is too small. objdump shows that there are instructions which would require up to 75 bytes buffer (with current formating). 128 bytes "ought to be enough for anybody". Also replaces 8 spaces with a single tab to reduce the memory footprint. Fixes the following KASAN finding: BUG: KASAN: stack-out-of-bounds in number+0x3fe/0x538 Write of size 1 at addr 000000005a4a75a0 by task bash/1282 CPU: 1 PID: 1282 Comm: bash Not tainted 4.14.0+ #215 Hardware name: IBM 2964 N96 702 (z/VM 6.4.0) Call Trace: ([<000000000011eeb6>] show_stack+0x56/0x88) [<0000000000e1ce1a>] dump_stack+0x15a/0x1b0 [<00000000004e2994>] print_address_description+0xf4/0x288 [<00000000004e2cf2>] kasan_report+0x13a/0x230 [<0000000000e38ae6>] number+0x3fe/0x538 [<0000000000e3dfe4>] vsnprintf+0x194/0x948 [<0000000000e3ea42>] sprintf+0xa2/0xb8 [<00000000001198dc>] print_insn+0x374/0x500 [<0000000000119346>] show_code+0x4ee/0x538 [<000000000011f234>] show_registers+0x34c/0x388 [<000000000011f2ae>] show_regs+0x3e/0xa8 [<000000000011f502>] die+0x1ea/0x2e8 [<0000000000138f0e>] do_no_context+0x106/0x168 [<0000000000139a1a>] do_protection_exception+0x4da/0x7d0 [<0000000000e55914>] pgm_check_handler+0x16c/0x1c0 [<000000000090639e>] sysrq_handle_crash+0x46/0x58 ([<0000000000000007>] 0x7) [<00000000009073fa>] __handle_sysrq+0x102/0x218 [<0000000000907c06>] write_sysrq_trigger+0xd6/0x100 [<000000000061d67a>] proc_reg_write+0xb2/0x128 [<0000000000520be6>] __vfs_write+0xee/0x368 [<0000000000521222>] vfs_write+0x21a/0x278 [<000000000052156a>] SyS_write+0xda/0x178 [<0000000000e555cc>] system_call+0xc4/0x270 The buggy address belongs to the page: page:000003d1016929c0 count:0 mapcount:0 mapping: (null) index:0x0 flags: 0x0() raw: 0000000000000000 0000000000000000 0000000000000000 ffffffff00000000 raw: 0000000000000100 0000000000000200 0000000000000000 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: 000000005a4a7480: 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1 000000005a4a7500: 00 00 00 00 00 00 00 00 f2 f2 f2 f2 00 00 00 00 >000000005a4a7580: 00 00 00 00 f3 f3 f3 f3 00 00 00 00 00 00 00 00 ^ 000000005a4a7600: 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1 f8 f8 000000005a4a7680: f2 f2 f2 f2 f2 f2 f8 f8 f2 f2 f3 f3 f3 f3 00 00 ================================================================== Signed-off-by: Vasily Gorbik Signed-off-by: Martin Schwidefsky Signed-off-by: Greg Kroah-Hartman --- arch/s390/kernel/dis.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/s390/kernel/dis.c b/arch/s390/kernel/dis.c index d9970c1..2394557 100644 --- a/arch/s390/kernel/dis.c +++ b/arch/s390/kernel/dis.c @@ -1954,7 +1954,7 @@ void show_code(struct pt_regs *regs) { char *mode = user_mode(regs) ? "User" : "Krnl"; unsigned char code[64]; - char buffer[64], *ptr; + char buffer[128], *ptr; mm_segment_t old_fs; unsigned long addr; int start, end, opsize, hops, i; @@ -2017,7 +2017,7 @@ void show_code(struct pt_regs *regs) start += opsize; pr_cont("%s", buffer); ptr = buffer; - ptr += sprintf(ptr, "\n "); + ptr += sprintf(ptr, "\n\t "); hops++; } pr_cont("\n"); -- 2.7.4