Bug 90194

Summary:

Fix Valgrind error in drmPrimeHandleToFD

Product:

DRI

Reporter:

Guillaume Desmottes <guillaume.desmottes>

Component:

libdrm

Assignee:

Default DRI bug account <dri-devel>

Status:

RESOLVED FIXED

QA Contact:

Severity:

normal

Priority:

medium

Version:

XOrg git

Hardware:

Other

OS:

All

Whiteboard:

i915 platform:

i915 features:

Attachments:

Description	Flags
drmPrimeHandleToFD: initialize args.fd to 0	none
drmPrime*: initialize output args to 0	none
drmPrime*: initialize output args to 0	none

Description Guillaume Desmottes 2015-04-27 13:48:14 UTC

args.fd is left uninitialized making Valgrind angry.

==14518== Syscall param ioctl(generic) points to uninitialised byte(s)
==14518==    at 0x3EB84F6407: ioctl (syscall-template.S:81)
==14518==    by 0x3B01803B17: drmIoctl (xf86drm.c:175)
==14518==    by 0x3B01806A7B: drmPrimeHandleToFD (xf86drm.c:2701)
==14518==    by 0xDF0866D: drm_intel_bo_gem_export_to_prime (intel_bufmgr_gem.c:2729)
==14518==    by 0xDA92DF7: intel_query_image (intel_screen.c:563)
==14518==    by 0x32E484E64D: dri3_alloc_render_buffer (dri3_glx.c:926)
==14518==    by 0x32E484E64D: dri3_get_buffer.isra.10 (dri3_glx.c:1307)
==14518==    by 0x32E484F499: dri3_get_buffers (dri3_glx.c:1466)
==14518==    by 0xDAB0486: intel_update_image_buffers (brw_context.c:1475)
==14518==    by 0xDAB0486: intel_update_renderbuffers (brw_context.c:1167)
==14518==    by 0xDAB07B4: intel_prepare_render (brw_context.c:1188)
==14518==    by 0xDAB0906: intelMakeCurrent (brw_context.c:1031)
==14518==    by 0xDA51495: driBindContext (dri_util.c:538)
==14518==    by 0x32E484DAA9: dri3_bind_context (dri3_glx.c:145)
==14518==    by 0x32E481E5E6: MakeContextCurrent (glxcurrent.c:243)
==14518==    by 0x8052F3C: gst_gl_context_glx_activate (gstglcontext_glx.c:401)
==14518==    by 0x8036D51: gst_gl_context_activate (gstglcontext.c:632)
==14518==    by 0x803882C: gst_gl_context_create_thread (gstglcontext.c:1282)
==14518==    by 0x3EBB0703D4: g_thread_proxy (gthread.c:764)
==14518==    by 0x3EB8807529: start_thread (pthread_create.c:310)
==14518==    by 0x3EB850022C: clone (clone.S:109)
==14518==  Address 0xd793a18 is on thread 9's stack
==14518==  in frame #2, created by drmPrimeHandleToFD (xf86drm.c:2695)

Comment 1 Guillaume Desmottes 2015-04-27 13:49:54 UTC

Created attachment 115375 [details] [review]
drmPrimeHandleToFD: initialize args.fd to 0

Comment 2 Emil Velikov 2015-04-28 11:02:58 UTC

Hi Guillaume

With args.fd used for output this seems like a false positive. Alternative solution would be to make Valgrind aware of this. A similar issue exists for args.handle in drmPrimeFDToHandle.

I fear that not many people keep track of bugzilla, so please forward your patch to the dri-devel mailing list [1].

Thanks
Emil

[1] dri-devel@lists.freedesktop.org

Comment 3 Guillaume Desmottes 2015-04-28 14:38:59 UTC

Created attachment 115403 [details] [review]
drmPrime*: initialize output args to 0

Here is a patch for both functions. I agree it's probably a false positive but the fix is simple enough to be worth adding those extra lines and saving people the trouble of debugging those.

I'll send the patch to the list as well.

Comment 4 Pekka Paalanen 2015-04-28 17:07:38 UTC

If you initialize an fd, at least initialize it to the invalid file descriptor -1. Zero is a valid file descriptor and very often already an open one.

Comment 5 Guillaume Desmottes 2015-04-29 08:15:53 UTC

Created attachment 115430 [details] [review]
drmPrime*: initialize output args to 0

Comment 6 Emil Velikov 2015-05-28 16:03:18 UTC

Added an extra memclear(args) for each function and pushed to master.

Thanks
Emil

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