Message ID | 1491508681-30385-1-git-send-email-rabin.vincent@axis.com |
---|---|
State | New |
Headers | show |
On 06/04/2017 16:58, Rabin Vincent wrote: > From: Rabin Vincent <rabinv@axis.com> > > __deregister_frame_info_bases() calls free() while holding a mutex which > is also used from _Unwind_Find_FDE(). This leads to a deadlock if > AddressSanitizer uses _Unwind_Backtrace() from its free() > implementation. > > 2017-04-06 Rabin Vincent <rabinv@axis.com> > > [BZ #21357] > * sysdeps/generic/unwind-dw2-fde.c (__deregister_frame_info_bases): > Call free() outside of mutex. > > diff --git a/sysdeps/generic/unwind-dw2-fde.c b/sysdeps/generic/unwind-dw2-fde.c > index 2f0bcd2..104a255 100644 > --- a/sysdeps/generic/unwind-dw2-fde.c > +++ b/sysdeps/generic/unwind-dw2-fde.c > @@ -202,6 +202,7 @@ __deregister_frame_info_bases (void *begin) > { > struct object **p; > struct object *ob = 0; > + struct fde_vector *tofree = NULL; > > /* If .eh_frame is empty, we haven't registered. */ > if (*(uword *) begin == 0) > @@ -225,7 +226,7 @@ __deregister_frame_info_bases (void *begin) > { > ob = *p; > *p = ob->next; > - free (ob->u.sort); > + tofree = ob->u.sort; > goto out; > } > } > @@ -244,6 +245,7 @@ __deregister_frame_info_bases (void *begin) > > out: > __gthread_mutex_unlock (&object_mutex); > + free (tofree); > return (void *) ob; > } > hidden_def (__deregister_frame_info_bases) LGTM, I assume you actually tested on some platform, right? Do you have write access?
On Mon, Apr 10, 2017 at 11:40:07AM -0300, Adhemerval Zanella wrote: > On 06/04/2017 16:58, Rabin Vincent wrote: > > [BZ #21357] > > * sysdeps/generic/unwind-dw2-fde.c (__deregister_frame_info_bases): > > Call free() outside of mutex. > > LGTM, I assume you actually tested on some platform, right? Do you have write access? Yes, I tested it on a 32-bit MIPS platform. No, I don't have write access. Thanks.
On 13/04/2017 06:55, Rabin Vincent wrote: > On Mon, Apr 10, 2017 at 11:40:07AM -0300, Adhemerval Zanella wrote: >> On 06/04/2017 16:58, Rabin Vincent wrote: >>> [BZ #21357] >>> * sysdeps/generic/unwind-dw2-fde.c (__deregister_frame_info_bases): >>> Call free() outside of mutex. >> >> LGTM, I assume you actually tested on some platform, right? Do you have write access? > > Yes, I tested it on a 32-bit MIPS platform. No, I don't have write > access. > > Thanks. > Alright, I will check this in.
diff --git a/sysdeps/generic/unwind-dw2-fde.c b/sysdeps/generic/unwind-dw2-fde.c index 2f0bcd2..104a255 100644 --- a/sysdeps/generic/unwind-dw2-fde.c +++ b/sysdeps/generic/unwind-dw2-fde.c @@ -202,6 +202,7 @@ __deregister_frame_info_bases (void *begin) { struct object **p; struct object *ob = 0; + struct fde_vector *tofree = NULL; /* If .eh_frame is empty, we haven't registered. */ if (*(uword *) begin == 0) @@ -225,7 +226,7 @@ __deregister_frame_info_bases (void *begin) { ob = *p; *p = ob->next; - free (ob->u.sort); + tofree = ob->u.sort; goto out; } } @@ -244,6 +245,7 @@ __deregister_frame_info_bases (void *begin) out: __gthread_mutex_unlock (&object_mutex); + free (tofree); return (void *) ob; } hidden_def (__deregister_frame_info_bases)
From: Rabin Vincent <rabinv@axis.com> __deregister_frame_info_bases() calls free() while holding a mutex which is also used from _Unwind_Find_FDE(). This leads to a deadlock if AddressSanitizer uses _Unwind_Backtrace() from its free() implementation. 2017-04-06 Rabin Vincent <rabinv@axis.com> [BZ #21357] * sysdeps/generic/unwind-dw2-fde.c (__deregister_frame_info_bases): Call free() outside of mutex.