[Bug 1711337] Re: Firefox crashes at start on armv7L after 55.0.1 update

James Donald 1711337 at bugs.launchpad.net
Sun Mar 4 04:00:33 UTC 2018

There was a typo in my above post, should say javascript.enabled, but
I'll assume you didn't have the extra dot when tried yesterday.

> I installed debug symbols

I just realized this makes it sound like you installed firefox-dbg,
which would give incorrect addresses because those symbols are for the
public apt binary. Do you mean that you *rebuilt* with debug symbols

> Can you check where that "crashes obscurely elsewhere" crashed ?

My NOP test earlier was flawed because it did not get the program
counter back onto a 4-byte aligned instruction + switch out of Thumb
mode. The fix was to hexedit in the thumb instructions 0020; 0047 (movs
r0, #0; bx r0). With this, Firefox 58 continues further on and then
crashes here:

   0x0040517c <_start+0>:	4f f0 00 0b	mov.w	r11, #0
   0x00405180 <_start+4>:	4f f0 00 0e	mov.w	lr, #0
   0x00405184 <_start+8>:	02 bc	pop	{r1}
   0x00405186 <_start+10>:	6a 46	mov	r2, sp
   0x00405188 <_start+12>:	04 b4	push	{r2}
   0x0040518a <_start+14>:	01 b4	push	{r0}
   0x0040518c <_start+16>:	df f8 24 a0	ldr.w	r10, [pc, #36]	; 0x4051b4 <_start+56

Firefox 59 crashes at the same instruction sequence, although the
addresses are of course different.

Getting a backtrace with symbols: Unfortunately for me if I install
firefox-dbg, firefox -g just hangs indefinitely. I thought this was due
to the limit of 1 GB RAM on a Raspberry Pi 3, but it doesn't get any
further even if I add gigabytes of swap space or wait a while.

It's also possible that the crash you're hitting is in the neighborhood
of the other one we were avoiding on Firefox 57 by specifically
installing the 14.04 package. The 16.04 packages of 57, 58, and 59 don't
even hit the SkJumper bug, instead crashing at an earlier point on this:

=> 0xf314e830:	c1 e9 00 23	strd	r2, r3, [r1]
   0xf314e834:	05 9b	ldr	r3, [sp, #20]
   0xf314e836:	06 9a	ldr	r2, [sp, #24]
   0xf314e838:	1a 60	str	r2, [r3, #0]
   0xf314e83a:	9d f8 38 30	ldrb.w	r3, [sp, #56]	; 0x38

Although this does not appear the same as the crash on your custom
build, interestingly in both cases the segfaulting instruction is
precisely strd r2, r3, [r1]

To confirm if you're actually getting past the SkJumper problem point,
after a few seconds the Firefox window frame should appear on the screen
before it crashes. That's the behavior on
firefox_58.0+build6-0ubuntu0.14.04.1_armhf.deb currently while
firefox_58.0.2+build1_0ubuntu0.16.04.1_armhf.deb just aborts before
getting that far.

You received this bug notification because you are a member of Mozilla
Bugs, which is subscribed to the bug report.

  Firefox crashes at start on armv7L after 55.0.1 update

To manage notifications about this bug go to:

More information about the Ubuntu-mozillateam-bugs mailing list