Date: Tue, 13 Feb 2024 02:58:09 +0200 From: Konstantin Belousov <kib@freebsd.org> To: Alexander Leidinger <alexleidingerde@gmail.com> Cc: current@freebsd.org Subject: Re: segfault in ld-elf.so.1 Message-ID: <Zcq-oU_4X7o_TfND@kib.kiev.ua> In-Reply-To: <ZcnqtY0dQoed9yjw@kib.kiev.ua> References: <1707730081-90734-mlmmj-4d88f1fd@FreeBSD.org> <CAJg7qzFV2bY14tn1-wdpeBb5W1XeZ7v6bk3Qhf5A=hV98kSXFw@mail.gmail.com> <ZcnqtY0dQoed9yjw@kib.kiev.ua>
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On Mon, Feb 12, 2024 at 11:54:02AM +0200, Konstantin Belousov wrote:
> On Mon, Feb 12, 2024 at 10:35:56AM +0100, Alexander Leidinger wrote:
> > Hi,
> >
> > dovecot (and no other program I use on this machine... at least not that I
> > notice it) segfaults in ld-elf.so.1 after an update from 2024-01-18-092730
> > to 2024-02-10-144617 (and now 2024-02-11-212006 in the hope the issue would
> > have been fixed by changes to libc/libsys since 2024-02-10-144617). The
> > issue shows up when I try to do an IMAP login. A successful authentication
> > starts the imap process which immediately segfaults.
> >
> > I didn't recompile dovecot for the initial update, but I did now to rule
> > out a regression in this area (and to get access via imap do my normal mail
> > account).
> >
> >
> > Backtrace:
> The backtrace looks incomplete. It might be the case of infinite recursion,
> but I cannot claim it from the trace.
>
> Does the program segfault if you run it manually? If yes, please provide
> me with the tarball of the binary and all required shared libs, including
> base system libraries, from your machine.
Regardless of my request, you might try the following. Note that I did
not tested the patch, ensure that you have a way to recover ld-elf.so.1
if something goes wrong.
diff --git a/libexec/rtld-elf/rtld.c b/libexec/rtld-elf/rtld.c
index 24abc4580f53..2ff6455c87fc 100644
--- a/libexec/rtld-elf/rtld.c
+++ b/libexec/rtld-elf/rtld.c
@@ -2583,7 +2583,7 @@ static void
load_filtees(Obj_Entry *obj, int flags, RtldLockState *lockstate)
{
- if (!obj->filtees_loaded) {
+ if (!obj->filtees_loaded && (flags & RTLD_LO_NOFILTEES) == 0) {
lock_restart_for_upgrade(lockstate);
load_filtee1(obj, obj->needed_filtees, flags, lockstate);
load_filtee1(obj, obj->needed_aux_filtees, flags, lockstate);
@@ -4479,6 +4479,7 @@ get_program_var_addr(const char *name, RtldLockState *lockstate)
symlook_init(&req, name);
req.lockstate = lockstate;
+ req.flags |= SYMLOOK_VAR;
donelist_init(&donelist);
if (symlook_global(&req, &donelist) != 0)
return (NULL);
@@ -4690,6 +4691,22 @@ symlook_needed(SymLook *req, const Needed_Entry *needed, DoneList *dlp)
return (ESRCH);
}
+static int
+symlook_obj_load_filtees(SymLook *req, SymLook *req1, const Obj_Entry *obj,
+ Needed_Entry *needed)
+{
+ DoneList donelist;
+ int flags, res;
+
+ flags = (req->flags & SYMLOOK_EARLY) != 0 ? RTLD_LO_EARLY : 0;
+ flags |= (req->flags & SYMLOOK_VAR) != 0 ? RTLD_LO_NOFILTEES : 0;
+ load_filtees(__DECONST(Obj_Entry *, obj), flags, req->lockstate);
+ donelist_init(&donelist);
+ symlook_init_from_req(req1, req);
+ res = symlook_needed(req1, needed, &donelist);
+ return (res);
+}
+
/*
* Search the symbol table of a single shared object for a symbol of
* the given name and version, if requested. Returns a pointer to the
@@ -4702,9 +4719,8 @@ symlook_needed(SymLook *req, const Needed_Entry *needed, DoneList *dlp)
int
symlook_obj(SymLook *req, const Obj_Entry *obj)
{
- DoneList donelist;
SymLook req1;
- int flags, res, mres;
+ int res, mres;
/*
* If there is at least one valid hash at this point, we prefer to
@@ -4719,11 +4735,8 @@ symlook_obj(SymLook *req, const Obj_Entry *obj)
if (mres == 0) {
if (obj->needed_filtees != NULL) {
- flags = (req->flags & SYMLOOK_EARLY) ? RTLD_LO_EARLY : 0;
- load_filtees(__DECONST(Obj_Entry *, obj), flags, req->lockstate);
- donelist_init(&donelist);
- symlook_init_from_req(&req1, req);
- res = symlook_needed(&req1, obj->needed_filtees, &donelist);
+ res = symlook_obj_load_filtees(req, &req1, obj,
+ obj->needed_filtees);
if (res == 0) {
req->sym_out = req1.sym_out;
req->defobj_out = req1.defobj_out;
@@ -4731,11 +4744,8 @@ symlook_obj(SymLook *req, const Obj_Entry *obj)
return (res);
}
if (obj->needed_aux_filtees != NULL) {
- flags = (req->flags & SYMLOOK_EARLY) ? RTLD_LO_EARLY : 0;
- load_filtees(__DECONST(Obj_Entry *, obj), flags, req->lockstate);
- donelist_init(&donelist);
- symlook_init_from_req(&req1, req);
- res = symlook_needed(&req1, obj->needed_aux_filtees, &donelist);
+ res = symlook_obj_load_filtees(req, &req1, obj,
+ obj->needed_aux_filtees);
if (res == 0) {
req->sym_out = req1.sym_out;
req->defobj_out = req1.defobj_out;
diff --git a/libexec/rtld-elf/rtld.h b/libexec/rtld-elf/rtld.h
index e8b15095812b..77776f241290 100644
--- a/libexec/rtld-elf/rtld.h
+++ b/libexec/rtld-elf/rtld.h
@@ -298,6 +298,7 @@ TAILQ_HEAD(obj_entry_q, Struct_Obj_Entry);
#define SYMLOOK_EARLY 0x04 /* Symlook is done during initialization. */
#define SYMLOOK_IFUNC 0x08 /* Allow IFUNC processing in
reloc_non_plt(). */
+#define SYMLOOK_VAR 0x10
/* Flags for load_object(). */
#define RTLD_LO_NOLOAD 0x01 /* dlopen() specified RTLD_NOLOAD. */
@@ -309,6 +310,8 @@ TAILQ_HEAD(obj_entry_q, Struct_Obj_Entry);
initialization during the image start. */
#define RTLD_LO_IGNSTLS 0x40 /* Do not allocate static TLS */
#define RTLD_LO_DEEPBIND 0x80 /* Force symbolic for this object */
+#define RTLD_LO_NOFILTEES 0x100 /* Skip loading filtees, sym resolution
+ from dlopen() */
/*
* Symbol cache entry used during relocation to avoid multiple lookups
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