Your message dated Mon, 10 Aug 2026 12:18:57 +0000 with message-id <[email protected]> and subject line Bug#1142771: fixed in webkit2gtk 2.53.90-1 has caused the Debian Bug report #1142771, regarding webkit2gtk: disable-nvidia-dmabuf.patch leaves backing store null, crashing WebKitGTK apps on NVIDIA to be marked as done.
This means that you claim that the problem has been dealt with. If this is not the case it is now your responsibility to reopen the Bug report if necessary, and/or fix the problem forthwith. (NB: If you are a system administrator and have no idea what this message is talking about, this may indicate a serious mail system misconfiguration somewhere. Please contact [email protected] immediately.) -- 1142771: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1142771 Debian Bug Tracking System Contact [email protected] with problems
--- Begin Message ---Source: webkit2gtk Severity: important Tags: patch On systems using the proprietary NVIDIA driver, any WebKitGTK application crashes with SIGSEGV the first time page content requires a compositing layer. disable-nvidia-dmabuf.patch adds its isNVIDIA() check before mode.add(RendererBufferTransportMode::SharedMemory), so on NVIDIA the function returns with an empty mode rather than with SharedMemory only: rendererBufferTransportMode() -> empty checkRequirements() -> false (silently, no warning) AcceleratedBackingStore::create() -> nullptr priv->acceleratedBackingStore -> NULL webkitWebViewBaseEnterAcceleratedCompositingMode() then dereferences that pointer, guarded only by an ASSERT that compiles out in release builds: ASSERT(webkitWebViewBase->priv->acceleratedBackingStore); webkitWebViewBase->priv->acceleratedBackingStore->update(layerTreeContext); Backtrace (libwebkit2gtk-4.1-0 2.52.3-0ubuntu0.24.04.1 with dbgsym): #0 AcceleratedBackingStore::update() AcceleratedBackingStore.cpp:808 #1 WebPageProxy::enterAcceleratedCompositingMode() #2 DrawingAreaProxyCoordinatedGraphics::enterAcceleratedCompositingMode() #3 DrawingAreaProxy::didReceiveMessage() <- IPC Messages::DrawingAreaProxy::EnterAcceleratedCompositingMode The intent of the patch is to disable the hardware DMABuf transport, not the software one. Moving the check three lines down keeps SharedMemory, which is what the backing store needs, and puts NVIDIA on the same path as the existing WEBKIT_DMABUF_RENDERER_FORCE_SHM escape hatch immediately below it: --- a/debian/patches/disable-nvidia-dmabuf.patch +++ b/debian/patches/disable-nvidia-dmabuf.patch @@ - if (isNVIDIA()) - return; - mode.add(RendererBufferTransportMode::SharedMemory); + if (isNVIDIA()) + return; + const char* forceSHM = getenv("WEBKIT_DMABUF_RENDERER_FORCE_SHM"); Verification on affected hardware (GeForce RTX 3050 Ti, driver 580.173.02, X11, Ubuntu 24.04, libwebkit2gtk-4.1-0 2.52.3-0ubuntu0.24.04.1). Values read from the running process and from the core dump: mode = {} (current) create() = 0x0 -> SIGSEGV mode = {SHM, HW} (WEBKIT_FORCE_DMABUF_RENDERER=1) no crash, blank window mode = {SharedMemory} renders, no crash The third row is the state the proposed change produces. I reproduced it with WEBKIT_FORCE_DMABUF_RENDERER=1 WEBKIT_DMABUF_RENDERER_FORCE_SHM=1 rather than by rebuilding the package, so the resulting mode is identical but isNVIDIA() is short-circuited instead of running and returning afterwards. I have not built a patched webkit2gtk to confirm the built artifact. I could not determine why the check was originally placed before the SharedMemory line. One possibility is that an empty mode still had a usable fallback when the patch was written and that fallback has since been removed; if SharedMemory must also be disabled on NVIDIA for a reason I am not aware of, then the fix belongs instead in the null handling in webkitWebViewBaseEnterAcceleratedCompositingMode(). Existing references: Debian #1039720, WebKit #262607, WebKit PR 18614 (which does not appear to have landed upstream -- the 2.52.3 tag has no isNVIDIA()). Workaround for affected users, forcing EGL to Mesa so isNVIDIA() is false: __EGL_VENDOR_LIBRARY_FILENAMES=/usr/share/glvnd/egl_vendor.d/50_mesa.json Kyle W. Santiago CTO [email protected] [Website](https://privkey.io/) | [GitHub](https://github.com/privkeyio) | [LinkedIn](https://www.linkedin.com/in/kwsantiago/) | [PGP](https://keyserver.ubuntu.com/pks/lookup?op=vindex&search=0x23ae8a8ea7e24e38)
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--- Begin Message ---Source: webkit2gtk Source-Version: 2.53.90-1 Done: Alberto Garcia <[email protected]> We believe that the bug you reported is fixed in the latest version of webkit2gtk, which is due to be installed in the Debian FTP archive. A summary of the changes between this version and the previous one is attached. Thank you for reporting the bug, which will now be closed. If you have further comments please address them to [email protected], and the maintainer will reopen the bug report if appropriate. Debian distribution maintenance software pp. Alberto Garcia <[email protected]> (supplier of updated webkit2gtk package) (This message was generated automatically at their request; if you believe that there is a problem with it please contact the archive administrators by mailing [email protected]) -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 Format: 1.8 Date: Mon, 10 Aug 2026 13:44:37 +0200 Source: webkit2gtk Architecture: source Version: 2.53.90-1 Distribution: experimental Urgency: medium Maintainer: Debian WebKit Maintainers <[email protected]> Changed-By: Alberto Garcia <[email protected]> Closes: 1142771 Changes: webkit2gtk (2.53.90-1) experimental; urgency=medium . * New upstream development release. * debian/copyright: - Update copyright information of all files. * debian/libwebkit2gtk-4.1-0.symbols: - Update symbols. * debian/patches/disable-dmabuf-nvidia.patch: - Use the SHM transport with NVIDIA GPUs (Closes: #1142771). Checksums-Sha1: e94d6b00ca33288988f32d7651ffd5ccc903f4a7 4724 webkit2gtk_2.53.90-1.dsc ad5088452956adf054059dbb24e140bb8c5dcf2b 49850104 webkit2gtk_2.53.90.orig.tar.xz c593f98600832c8785131228c414db4bdee77b9d 833 webkit2gtk_2.53.90.orig.tar.xz.asc 6438b4ecdb3a4ccc38ea02567a2dafbbb966253d 94076 webkit2gtk_2.53.90-1.debian.tar.xz f67d1d301b7047f8d51cd5e356ea56b3f5b1af61 16480 webkit2gtk_2.53.90-1_source.buildinfo Checksums-Sha256: 9e46faa7d339e22c490b0d41696b8733316065a7e128e777b7ea9e9ae791315b 4724 webkit2gtk_2.53.90-1.dsc 56b99f7b482221da2b6acc307cac3b8fb777e8dcb7720c56d5d77161a837c8e6 49850104 webkit2gtk_2.53.90.orig.tar.xz 56e09e68d795ac38ba1b7a4fed9858bf33601ac2d79bb226fb034bc379e4a962 833 webkit2gtk_2.53.90.orig.tar.xz.asc 942e869e7d9570e932213767c75efedb44d0b9038b91462e82e8fd64e5b9d4a0 94076 webkit2gtk_2.53.90-1.debian.tar.xz 76671f050f6a894833b183f06553e1257dbf2b0ec2c1ab7da6d07bc70798834d 16480 webkit2gtk_2.53.90-1_source.buildinfo Files: fb54a98afc4a07b9f8c18a21acf6009e 4724 web optional webkit2gtk_2.53.90-1.dsc ecf60feeae32986ee101cdd11258864b 49850104 web optional webkit2gtk_2.53.90.orig.tar.xz c0ca4a69871cf567a72421ec184e63e4 833 web optional webkit2gtk_2.53.90.orig.tar.xz.asc 140d2f0d1fc41eb0e1f6b595142ed3b9 94076 web optional webkit2gtk_2.53.90-1.debian.tar.xz fc874c5ebc6b5b5eeb62e002c51c139c 16480 web optional webkit2gtk_2.53.90-1_source.buildinfo -----BEGIN PGP SIGNATURE----- iQIzBAEBCgAdFiEEYrwugQBKzlHMYFizAAyEYu0C2AIFAmp5vNsACgkQAAyEYu0C 2AI4xg/+NR7nXXfM/ID1tVpuG1hfzt++lUSCDKm7dVFt9uEjucD5Na0UGligqXXS eSS5hGUlOiohDiD41eq6l7tYeoefasOg0i5v90BMMD7i5P8aPkbilea3VDa3Zb0M f5ueQdBtDcwSLhlcdSvj4TnlR7MeioHiJVXpEB+X/2cmzVP6346hUj1oKHEel0j6 PKLIkm2AVMK+lhRAf8QekGomDOwljLB0AQre9o9WlgDY347D0vGmNWzuXEJlchPA dmW0ltPxU4Fpusmq9v8BJ/fbRucHxuVnxWabIrYrd3lnr8Og7ryChZeKJFNXmGXO Tx/td8+04Z3tbnHjOIHBuHXslcw0sQXb9HEwZK8GxrMGK72Nm9mwxHy6dlSxGdxU aFmOSnLL1S06X5V5h3ttL4SJU0SAVIi2vMzuCAH0lMlwF8kvwWnP63nJQdqAb4LG LVfWmoX8Zl9y47QGfAUm8yNApAeOWxmhtAludg8qTbw51ApLJ81trjVaAMfKyKEM eVu0Po/vHgGqNauRV9YXOiln9iPrlgNYrZRkok1d7R/Xio9+nj0QMuYlp+1IjQ4I MgY03ufgfU/7vYTXrORZfGZH8JT4f6uburVsSzKnrOZUfZd5e3PihVm7y05y0nzd aw1hCJMGetoS3Y9NbFqQdc73c3Wb2c7XSW+AqIJ+8CbcobbaNBY= =ggAf -----END PGP SIGNATURE-----
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