Messages in this thread | | | From | Dmitry Safonov <> | Date | Thu, 2 Aug 2018 20:53:41 +0100 | Subject | Re: [PATCH RESEND] exec: don't force_sigsegv processes with a pending fatal signal |
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Hi Ivan,
2018-07-31 1:56 GMT+01:00 Ivan Delalande <colona@arista.com>: > We were seeing unexplained segfaults in coreutils processes and other > basic utilities that we tracked down to binfmt_elf failing to load > segments for ld.so. Digging further, the actual problem seems to occur > when a process gets sigkilled while it is still being loaded by the > kernel. In our case when _do_page_fault goes for a retry it will return > early as it first checks for fatal_signal_pending(), so load_elf_interp > also returns with error and as a result search_binary_handler will > force_sigsegv() which is pretty confusing as nothing actually failed > here. > > Fixes: 19d860a140be ("handle suicide on late failure exits in execve() in search_binary_handler()") > Reference: https://lkml.org/lkml/2013/2/14/5 > Signed-off-by: Ivan Delalande <colona@arista.com>
+Cc: Oleg Nesterov <oleg@redhat.com> +Cc: Andy Lutomirski <luto@kernel.org>
> --- > fs/exec.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/fs/exec.c b/fs/exec.c > index bdd0eacefdf5..6e8007edbb2d 100644 > --- a/fs/exec.c > +++ b/fs/exec.c > @@ -1656,7 +1656,8 @@ int search_binary_handler(struct linux_binprm *bprm) > if (retval < 0 && !bprm->mm) { > /* we got to flush_old_exec() and failed after it */ > read_unlock(&binfmt_lock); > - force_sigsegv(SIGSEGV, current); > + if (!fatal_signal_pending(current)) > + force_sigsegv(SIGSEGV, current);
I would suggest to add something like: : if (print_fatal_signals) : pr_info("load_binary() failed: %d\n", retval);
It was interesting to catch that it actually segfaults during loading, probably will save someone a couple of minutes too ;-)
> return retval; > } > if (retval != -ENOEXEC || !bprm->file) {
Thanks, Dmitry
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