From 6a2b27c0f512619b0e7a769a18a0fb05bb3789a5 Mon Sep 17 00:00:00 2001 From: Arnaldo Carvalho de Melo Date: Tue, 18 Jun 2024 10:37:30 -0300 Subject: [PATCH] core: Initialize cu->node with INIT_LIST_HEAD() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit In cu__new() zalloc() is used defensively, and that helped catch this problem where we assume that a cu us in the cus list of cu instances, but that is not the case when we use cus__merge_and_process_cu(), for instance when loading files created by clang with LTO, as reported by Peter Jung and narrowed down by Nathan Chancellor. If we use INIT_LIST_HEAD() in cu__new() to initialize cu->node, which is what we do with other lists and nodes there, then the unconditional removal using list_del_init() will be a no-op and removing something not on the cus list of cu instances will not cause problems, just keep an unconsistent cus->nr_entries field. So lets just have this fix in first, keeping Nathan's Tested-by and then do the a bit more involved fix of either adding that cu to the cus list or checking at removal time if it is there. Program received signal SIGSEGV, Segmentation fault. 0x00007ffff7f1e13e in __list_del (prev=0x0, next=0x0) at /home/acme/git/pahole/list.h:106 106 next->prev = prev; (gdb) bt #0 0x00007ffff7f1e13e in __list_del (prev=0x0, next=0x0) at /home/acme/git/pahole/list.h:106 #1 0x00007ffff7f1e176 in list_del_init (entry=0x417980) at /home/acme/git/pahole/list.h:165 #2 0x00007ffff7f1f8f9 in __cus__remove (cus=0x4142a0, cu=0x417980) at /home/acme/git/pahole/dwarves.c:527 #3 0x00007ffff7f1f92b in cus__remove (cus=0x4142a0, cu=0x417980) at /home/acme/git/pahole/dwarves.c:533 #4 0x00007ffff7f3d01c in cus__finalize (cus=0x4142a0, cu=0x417980, conf=0x4133c0 , thr_data=0x0) at /home/acme/git/pahole/dwarf_loader.c:3040 #5 0x00007ffff7f3e05c in cus__merge_and_process_cu (cus=0x4142a0, conf=0x4133c0 , mod=0x415cf0, dw=0x416110, elf=0x414380, filename=0x7fffffffe3f7 "cast_common.ko", build_id=0x416680 "\265D\371U\213\373u|\037\250\242\032\271\365⒜]y\023", build_id_len=20, type_dcu=0x0) at /home/acme/git/pahole/dwarf_loader.c:3482 #6 0x00007ffff7f3e218 in cus__load_module (cus=0x4142a0, conf=0x4133c0 , mod=0x415cf0, dw=0x416110, elf=0x414380, filename=0x7fffffffe3f7 "cast_common.ko") at /home/acme/git/pahole/dwarf_loader.c:3521 #7 0x00007ffff7f3e396 in cus__process_dwflmod (dwflmod=0x415cf0, userdata=0x415d00, name=0x415ea0 "cast_common.ko", base=65536, arg=0x7fffffffde40) at /home/acme/git/pahole/dwarf_loader.c:3581 #8 0x00007ffff7eb4609 in dwfl_getmodules (dwfl=0x414300, callback=0x7ffff7f3e2ec , arg=0x7fffffffde40, offset=0) at ../libdwfl/dwfl_getmodules.c:86 #9 0x00007ffff7f3e4c5 in cus__process_file (cus=0x4142a0, conf=0x4133c0 , fd=3, filename=0x7fffffffe3f7 "cast_common.ko") at /home/acme/git/pahole/dwarf_loader.c:3647 #10 0x00007ffff7f3e5cd in dwarf__load_file (cus=0x4142a0, conf=0x4133c0 , filename=0x7fffffffe3f7 "cast_common.ko") at /home/acme/git/pahole/dwarf_loader.c:3684 #11 0x00007ffff7f232df in cus__load_file (cus=0x4142a0, conf=0x4133c0 , filename=0x7fffffffe3f7 "cast_common.ko") at /home/acme/git/pahole/dwarves.c:2134 #12 0x00007ffff7f23e8b in cus__load_files (cus=0x4142a0, conf=0x4133c0 , filenames=0x7fffffffe0f0) at /home/acme/git/pahole/dwarves.c:2637 #13 0x000000000040aec0 in main (argc=2, argv=0x7fffffffe0e8) at /home/acme/git/pahole/pahole.c:3805 (gdb) fr 1 #1 0x00007ffff7f1e176 in list_del_init (entry=0x417980) at /home/acme/git/pahole/list.h:165 165 __list_del(entry->prev, entry->next); (gdb) p entry $1 = (struct list_head *) 0x417980 (gdb) p entry->next $2 = (struct list_head *) 0x0 (gdb) p entry->prev $3 = (struct list_head *) 0x0 Closes: https://github.com/acmel/dwarves/issues/53 Closes: https://gitlab.archlinux.org/archlinux/packaging/packages/pahole/-/issues/1 Tested-by: Nathan Chancellor Link: https://lore.kernel.org/all/20240617210810.GA1877676@thelio-3990X Signed-off-by: Arnaldo Carvalho de Melo --- dwarves.c | 1 + 1 file changed, 1 insertion(+) diff --git a/dwarves.c b/dwarves.c index 1ec259f5..823a0152 100644 --- a/dwarves.c +++ b/dwarves.c @@ -739,6 +739,7 @@ struct cu *cu__new(const char *name, uint8_t addr_size, cu->dfops = NULL; INIT_LIST_HEAD(&cu->tags); INIT_LIST_HEAD(&cu->tool_list); + INIT_LIST_HEAD(&cu->node); cu->addr_size = addr_size; cu->extra_dbg_info = 0;