On Sat, Jun 29, 2019 at 2:22 AM Vasily Gorbik <gor@xxxxxxxxxxxxx> wrote: > > gcc asan instrumentation emits the following sequence to store frame pc > when the kernel is built with CONFIG_RELOCATABLE: > debug/vsprintf.s: > .section .data.rel.ro.local,"aw" > .align 8 > .LC3: > .quad .LASANPC4826@GOTOFF > .text > .align 8 > .type number, @function > number: > .LASANPC4826: > > and in case reloc is issued for LASANPC label it also gets into .symtab > with the same address as actual function symbol: > $ nm -n vmlinux | grep 0000000001397150 > 0000000001397150 t .LASANPC4826 > 0000000001397150 t number > > In the end kernel backtraces are almost unreadable: > [ 143.748476] Call Trace: > [ 143.748484] ([<000000002da3e62c>] .LASANPC2671+0x114/0x190) > [ 143.748492] [<000000002eca1a58>] .LASANPC2612+0x110/0x160 > [ 143.748502] [<000000002de9d830>] print_address_description+0x80/0x3b0 > [ 143.748511] [<000000002de9dd64>] __kasan_report+0x15c/0x1c8 > [ 143.748521] [<000000002ecb56d4>] strrchr+0x34/0x60 > [ 143.748534] [<000003ff800a9a40>] kasan_strings+0xb0/0x148 [test_kasan] > [ 143.748547] [<000003ff800a9bba>] kmalloc_tests_init+0xe2/0x528 [test_kasan] > [ 143.748555] [<000000002da2117c>] .LASANPC4069+0x354/0x748 > [ 143.748563] [<000000002dbfbb16>] do_init_module+0x136/0x3b0 > [ 143.748571] [<000000002dbff3f4>] .LASANPC3191+0x2164/0x25d0 > [ 143.748580] [<000000002dbffc4c>] .LASANPC3196+0x184/0x1b8 > [ 143.748587] [<000000002ecdf2ec>] system_call+0xd8/0x2d8 > > Since LASANPC labels are not even unique and get into .symtab only due > to relocs filter them out in kallsyms. > > Signed-off-by: Vasily Gorbik <gor@xxxxxxxxxxxxx> Applied to linux-kbuild. Thanks. > --- > scripts/kallsyms.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c > index e17837f1d3f2..ae6504d07fd6 100644 > --- a/scripts/kallsyms.c > +++ b/scripts/kallsyms.c > @@ -150,6 +150,9 @@ static int read_symbol(FILE *in, struct sym_entry *s) > /* exclude debugging symbols */ > else if (stype == 'N' || stype == 'n') > return -1; > + /* exclude s390 kasan local symbols */ > + else if (!strncmp(sym, ".LASANPC", 8)) > + return -1; > > /* include the type field in the symbol name, so that it gets > * compressed together */ > -- > 2.21.0 > -- Best Regards Masahiro Yamada
