d1111eb0c1
ProcRenderAddGlyphs() adds the glyph to the glyphset using AddGlyph() and
then frees it using FreeGlyph() to decrease the reference count, after
AddGlyph() has increased it.
AddGlyph() however may chose to reuse an existing glyph if it's already
in the glyphSet, and free the glyph that was given, in which case the
caller function, ProcRenderAddGlyphs() will call FreeGlyph() on an
already freed glyph, as reported by ASan:
READ of size 4 thread T0
#0 in FreeGlyph xserver/render/glyph.c:252
#1 in ProcRenderAddGlyphs xserver/render/render.c:1174
#2 in Dispatch xserver/dix/dispatch.c:546
#3 in dix_main xserver/dix/main.c:271
#4 in main xserver/dix/stubmain.c:34
#5 in __libc_start_call_main ../sysdeps/nptl/libc_start_call_main.h:58
#6 in __libc_start_main_impl ../csu/libc-start.c:360
#7 (/usr/bin/Xwayland+0x44fe4)
Address is located 0 bytes inside of 64-byte region
freed by thread T0 here:
#0 in __interceptor_free libsanitizer/asan/asan_malloc_linux.cpp:52
#1 in _dixFreeObjectWithPrivates xserver/dix/privates.c:538
#2 in AddGlyph xserver/render/glyph.c:295
#3 in ProcRenderAddGlyphs xserver/render/render.c:1173
#4 in Dispatch xserver/dix/dispatch.c:546
#5 in dix_main xserver/dix/main.c:271
#6 in main xserver/dix/stubmain.c:34
#7 in __libc_start_call_main ../sysdeps/nptl/libc_start_call_main.h:58
previously allocated by thread T0 here:
#0 in __interceptor_malloc libsanitizer/asan/asan_malloc_linux.cpp:69
#1 in AllocateGlyph xserver/render/glyph.c:355
#2 in ProcRenderAddGlyphs xserver/render/render.c:1085
#3 in Dispatch xserver/dix/dispatch.c:546
#4 in dix_main xserver/dix/main.c:271
#5 in main xserver/dix/stubmain.c:34
#6 in __libc_start_call_main ../sysdeps/nptl/libc_start_call_main.h:58
SUMMARY: AddressSanitizer: heap-use-after-free xserver/render/glyph.c:252 in FreeGlyph
To avoid that, make sure not to free the given glyph in AddGlyph().
v2: Simplify the test using the boolean returned from AddGlyph() (Michel)
v3: Simplify even more by not freeing the glyph in AddGlyph() (Peter)
Fixes:
|
||
|---|---|---|
| .gitlab-ci | ||
| composite | ||
| config | ||
| damageext | ||
| dbe | ||
| dix | ||
| doc | ||
| dri3 | ||
| exa | ||
| fb | ||
| glamor | ||
| glx | ||
| hw | ||
| include | ||
| m4 | ||
| man | ||
| mi | ||
| miext | ||
| os | ||
| present | ||
| pseudoramiX | ||
| randr | ||
| record | ||
| render | ||
| test | ||
| Xext | ||
| xfixes | ||
| Xi | ||
| xkb | ||
| .appveyor.yml | ||
| .dir-locals.el | ||
| .gitignore | ||
| .gitlab-ci.yml | ||
| .mailmap | ||
| .travis.yml | ||
| COPYING | ||
| meson.build | ||
| meson_options.txt | ||
| README.md | ||
| xorg-server.m4 | ||
| xorg-server.pc.in | ||
| xserver.ent.in | ||
X Server
The X server accepts requests from client applications to create windows, which are (normally rectangular) "virtual screens" that the client program can draw into.
Windows are then composed on the actual screen by the X server (or by a separate composite manager) as directed by the window manager, which usually communicates with the user via graphical controls such as buttons and draggable titlebars and borders.
For a comprehensive overview of X Server and X Window System, consult the following article: https://en.wikipedia.org/wiki/X_server
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