From: Vasily Gorbik gor@linux.ibm.com
[ Upstream commit 33177f01ca3fe550146bb9001bec2fd806b2f40c ]
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@linux.ibm.com Signed-off-by: Masahiro Yamada yamada.masahiro@socionext.com Signed-off-by: Sasha Levin sashal@kernel.org --- scripts/kallsyms.c | 3 +++ 1 file changed, 3 insertions(+)
diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c index 0c9c54b57515..31ed7f3f0e15 100644 --- a/scripts/kallsyms.c +++ b/scripts/kallsyms.c @@ -152,6 +152,9 @@ 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 */