From: Stephen Boyd <swboyd@xxxxxxxxxxxx> Subject: buildid: only consider GNU notes for build ID parsing Patch series "Add build ID to stacktraces", v6. This series adds the kernel's build ID[1] to the stacktrace header printed in oops messages, warnings, etc. and the build ID for any module that appears in the stacktrace after the module name. The goal is to make the stacktrace more self-contained and descriptive by including the relevant build IDs in the kernel logs when something goes wrong. This can be used by post processing tools like script/decode_stacktrace.sh and kernel developers to easily locate the debug info associated with a kernel crash and line up what line and file things started falling apart at. To show how this can be used I've included a patch to decode_stacktrace.sh that downloads the debuginfo from a debuginfod server. This also includes some patches to make the buildid.c file use more const arguments and consolidate logic into buildid.c from kdump. These are left to the end as they were mostly cleanup patches. Here's an example lkdtm stacktrace on arm64. WARNING: CPU: 4 PID: 3255 at drivers/misc/lkdtm/bugs.c:83 lkdtm_WARNING+0x28/0x30 [lkdtm] Modules linked in: lkdtm rfcomm algif_hash algif_skcipher af_alg xt_cgroup uinput xt_MASQUERADE CPU: 4 PID: 3255 Comm: bash Not tainted 5.11 #3 aa23f7a1231c229de205662d5a9e0d4c580f19a1 Hardware name: Google Lazor (rev3+) with KB Backlight (DT) pstate: 00400009 (nzcv daif +PAN -UAO -TCO BTYPE=--) pc : lkdtm_WARNING+0x28/0x30 [lkdtm] lr : lkdtm_do_action+0x24/0x40 [lkdtm] sp : ffffffc0134fbca0 x29: ffffffc0134fbca0 x28: ffffff92d53ba240 x27: 0000000000000000 x26: 0000000000000000 x25: 0000000000000000 x24: ffffffe3622352c0 x23: 0000000000000020 x22: ffffffe362233366 x21: ffffffe3622352e0 x20: ffffffc0134fbde0 x19: 0000000000000008 x18: 0000000000000000 x17: ffffff929b6536fc x16: 0000000000000000 x15: 0000000000000000 x14: 0000000000000012 x13: ffffffe380ed892c x12: ffffffe381d05068 x11: 0000000000000000 x10: 0000000000000000 x9 : 0000000000000001 x8 : ffffffe362237000 x7 : aaaaaaaaaaaaaaaa x6 : 0000000000000000 x5 : 0000000000000000 x4 : 0000000000000001 x3 : 0000000000000008 x2 : ffffff93fef25a70 x1 : ffffff93fef15788 x0 : ffffffe3622352e0 Call trace: lkdtm_WARNING+0x28/0x30 [lkdtm ed5019fdf5e53be37cb1ba7899292d7e143b259e] direct_entry+0x16c/0x1b4 [lkdtm ed5019fdf5e53be37cb1ba7899292d7e143b259e] full_proxy_write+0x74/0xa4 vfs_write+0xec/0x2e8 ksys_write+0x84/0xf0 __arm64_sys_write+0x24/0x30 el0_svc_common+0xf4/0x1c0 do_el0_svc_compat+0x28/0x3c el0_svc_compat+0x10/0x1c el0_sync_compat_handler+0xa8/0xcc el0_sync_compat+0x178/0x180 ---[ end trace 3d95032303e59e68 ]--- This patch (of 13): Some kernel elf files have various notes that also happen to have an elf note type of '3', which matches NT_GNU_BUILD_ID but the note name isn't "GNU". For example, this note trips up the existing logic: Owner Data size Description Xen 0x00000008 Unknown note type: (0x00000003) description data: 00 00 00 ffffff80 ffffffff ffffffff ffffffff ffffffff Let's make sure that it is a GNU note when parsing the build ID so that we can use this function to parse a vmlinux's build ID too. Link: https://lkml.kernel.org/r/20210511003845.2429846-1-swboyd@xxxxxxxxxxxx Link: https://lkml.kernel.org/r/20210511003845.2429846-2-swboyd@xxxxxxxxxxxx Fixes: bd7525dacd7e ("bpf: Move stack_map_get_build_id into lib") Signed-off-by: Stephen Boyd <swboyd@xxxxxxxxxxxx> Reported-by: Petr Mladek <pmladek@xxxxxxxx> Tested-by: Petr Mladek <pmladek@xxxxxxxx> Cc: Jiri Olsa <jolsa@xxxxxxxxxx> Cc: Alexei Starovoitov <ast@xxxxxxxxxx> Cc: Jessica Yu <jeyu@xxxxxxxxxx> Cc: Evan Green <evgreen@xxxxxxxxxxxx> Cc: Hsin-Yi Wang <hsinyi@xxxxxxxxxxxx> Cc: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> Cc: Baoquan He <bhe@xxxxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxxxx> Cc: Catalin Marinas <catalin.marinas@xxxxxxx> Cc: Dave Young <dyoung@xxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx> Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx> Cc: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx> Cc: Sasha Levin <sashal@xxxxxxxxxx> Cc: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Vivek Goyal <vgoyal@xxxxxxxxxx> Cc: Will Deacon <will@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- lib/buildid.c | 1 + 1 file changed, 1 insertion(+) --- a/lib/buildid.c~buildid-only-consider-gnu-notes-for-build-id-parsing +++ a/lib/buildid.c @@ -31,6 +31,7 @@ static inline int parse_build_id(void *p if (nhdr->n_type == BUILD_ID && nhdr->n_namesz == sizeof("GNU") && + !strcmp((char *)(nhdr + 1), "GNU") && nhdr->n_descsz > 0 && nhdr->n_descsz <= BUILD_ID_SIZE_MAX) { memcpy(build_id, _
