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imgui_freetype: Assert if glyph bitmap size exceed chunk size to avoid buffer overflow #5731

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imgui_freetype: Assert if glyph bitmap size exceed chunk size to avoid buffer overflow #5731

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cfillion
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FreeTypeFont::BlitGlyph may write past the destination buffer if the glyph cannot fit in BITMAP_BUFFERS_CHUNK_SIZE bytes (weird font or just by requesting a huge size).

#define IMGUI_ENABLE_FREETYPE
// ...
io.Fonts->AddFontFromFileTTF("/usr/share/fonts/TTF/DejaVuSans.ttf", 1<<16);

This PR makes it assert instead of corrupting memory.

ocornut pushed a commit that referenced this pull request Sep 30, 2022
@cfillion @ocornut
imgui_freetype: Assert if bitmap size exceed chunk size to avoid buff…
5884219 
…er overflow. (#5731)
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ocornut commented Sep 30, 2022

Thank you! I merged this as 5884219 and took the liberty to add a comment about the fact we could fairly easily support that use case by allocating an appropriately sized buffer. But as you suggested I believe this is likely only happening on incorrect sizing, so we'll mind this further if there's a use for it.
Thanks!

@ocornut ocornut closed this Sep 30, 2022
fangshun2004 added a commit to fangshun2004/imgui that referenced this pull request Sep 30, 2022
@fangshun2004
Squashed commit of the following:
b1f824b 
commit 5884219
Author: cfillion <[email protected]>
Date:   Wed Sep 28 23:37:39 2022 -0400

    imgui_freetype: Assert if bitmap size exceed chunk size to avoid buffer overflow. (ocornut#5731)

commit f2a522d
Author: ocornut <[email protected]>
Date:   Fri Sep 30 15:43:27 2022 +0200

    ImDrawList: Not using alloca() anymore, lift single polygon size limits. (ocornut#5704, ocornut#1811)

commit cc5058e
Author: ocornut <[email protected]>
Date:   Thu Sep 29 21:59:32 2022 +0200

    IO: Filter duplicate input events during the AddXXX() calls. (ocornut#5599, ocornut#4921)

commit fac8295
Author: ocornut <[email protected]>
Date:   Thu Sep 29 21:31:36 2022 +0200

    IO: remove ImGuiInputEvent::IgnoredAsSame (revert part of 839c310), will filter earlier in next commit. (ocornut#5599)

    Making it a separate commit as this leads to much indentation change.

commit 9e7f460
Author: ocornut <[email protected]>
Date:   Thu Sep 29 20:42:45 2022 +0200

    Fixed GetKeyName() for ImGuiMod_XXX values, made invalid MousePos display in log nicer.  (ocornut#4921, ocornut#456)

    Amend fd408c9

commit 0749453
Author: ocornut <[email protected]>
Date:   Thu Sep 29 19:51:54 2022 +0200

    Menus, Nav: Fixed not being able to close a menu with Left arrow when parent is not a popup. (ocornut#5730)

commit 9f6aae3
Author: ocornut <[email protected]>
Date:   Thu Sep 29 19:48:27 2022 +0200

    Nav: Fixed race condition pressing Esc during popup opening frame causing crash.

commit bd2355a
Author: ocornut <[email protected]>
Date:   Thu Sep 29 19:25:26 2022 +0200

    Menus, Nav: Fixed using left/right navigation when appending to an existing menu (multiple BeginMenu() call with same names). (ocornut#1207)

commit 3532ed1
Author: ocornut <[email protected]>
Date:   Thu Sep 29 18:07:35 2022 +0200

    Menus, Nav: Fixed keyboard/gamepad navigation occasionally erroneously landing on menu-item in parent when the parent is not a popup. (ocornut#5730)

    Replace BeginMenu/MenuItem swapping g.NavWindow with a more adequate ImGuiItemFlags_NoWindowHoverableCheck.
    Expecting more subtle issues to stem from this.
    Note that NoWindowHoverableCheck is not supported by IsItemHovered() but then IsItemHovered() on BeginMenu() never worked: fix should be easy in BeginMenu() + add test is IsItemHovered(), will do later

commit d5d7050
Author: ocornut <[email protected]>
Date:   Thu Sep 29 17:26:52 2022 +0200

    Various comments

    As it turns out, functions like IsItemHovered() won't work on an open BeginMenu() because LastItemData is overriden by BeginPopup(). Probably an easy fix.

commit e74a50f
Author: Andrew D. Zonenberg <[email protected]>
Date:   Wed Sep 28 08:19:34 2022 -0700

    Added GetGlyphRangesGreek() helper for Greek & Coptic glyph range. (ocornut#5676, ocornut#5727)

commit d17627b
Author: ocornut <[email protected]>
Date:   Wed Sep 28 17:38:41 2022 +0200

    InputText: leave state->Flags uncleared for the purpose of backends emitting an on-screen keyboard for passwords. (ocornut#5724)

commit 0a7054c
Author: ocornut <[email protected]>
Date:   Wed Sep 28 17:00:45 2022 +0200

    Backends: Win32: Convert WM_CHAR values with MultiByteToWideChar() when window class was registered as MBCS (not Unicode). (ocornut#5725, ocornut#1807, ocornut#471, ocornut#2815, ocornut#1060)

commit a229a7f
Author: ocornut <[email protected]>
Date:   Wed Sep 28 16:57:09 2022 +0200

    Examples: Win32: Always use RegisterClassW() to ensure windows are Unicode. (ocornut#5725)

commit e0330c1
Author: ocornut <[email protected]>
Date:   Wed Sep 28 14:54:38 2022 +0200

    Fonts, Text: Fixed wrapped-text not doing a fast-forward on lines above the clipping region. (ocornut#5720)

    which would result in an abnormal number of vertices created.

commit 4d4889b
Author: ocornut <[email protected]>
Date:   Wed Sep 28 12:42:06 2022 +0200

    Refactor CalcWordWrapPositionA() to take on the responsability of minimum character display. Add CalcWordWrapNextLineStartA(), simplify caller code.

    Should be no-op but incrementing IMGUI_VERSION_NUM just in case.
    Preparing for ocornut#5720

commit 5c4426c
Author: ocornut <[email protected]>
Date:   Wed Sep 28 12:22:34 2022 +0200

    Demo: Fixed Log & Console from losing scrolling position with Auto-Scroll when child is clipped. (ocornut#5721)

commit 12c0246
Author: ocornut <[email protected]>
Date:   Wed Sep 28 12:07:43 2022 +0200

    Removed support for 1.42-era IMGUI_DISABLE_INCLUDE_IMCONFIG_H / IMGUI_INCLUDE_IMCONFIG_H. (ocornut#255)

commit 73efcec
Author: ocornut <[email protected]>
Date:   Tue Sep 27 22:21:47 2022 +0200

    Examples: disable GL related warnings on Mac + amend to ignore list.

commit a725db1
Author: ocornut <[email protected]>
Date:   Tue Sep 27 18:47:20 2022 +0200

    Comments for flags discoverability + add to debug log (ocornut#3795, ocornut#4559)

commit 325299f
Author: ocornut <[email protected]>
Date:   Wed Sep 14 15:46:27 2022 +0200

    Backends: OpenGL: Add ability to #define IMGUI_IMPL_OPENGL_DEBUG. (ocornut#4468, ocornut#4825, ocornut#4832, ocornut#5127, ocornut#5655, ocornut#5709)

commit 56c3eae
Author: ocornut <[email protected]>
Date:   Tue Sep 27 14:24:21 2022 +0200

    ImDrawList: asserting on incorrect value for CurveTessellationTol (ocornut#5713)

commit 04316bd
Author: ocornut <[email protected]>
Date:   Mon Sep 26 16:32:09 2022 +0200

    ColorEdit3: fixed id collision leading to an assertion. (ocornut#5707)

commit c261dac
Author: ocornut <[email protected]>
Date:   Mon Sep 26 14:50:46 2022 +0200

    Demo: moved ShowUserGuide() lower in the file, to make main demo entry point more visible + fix using IMGUI_DEBUG_LOG() macros in if/else.

commit 51bbc70
Author: ocornut <[email protected]>
Date:   Mon Sep 26 14:44:26 2022 +0200

    Backends: SDL: Disable SDL 2.0.22 new "auto capture" which prevents drag and drop across windows, and don't capture mouse when drag and dropping. (ocornut#5710)

commit 7a9045d
Author: ocornut <[email protected]>
Date:   Mon Sep 26 11:55:07 2022 +0200

    Backends: WGPU: removed Emscripten version check (currently failing on CI, ensure why, and tbh its redundant/unnecessary with changes of wgpu api nowadays)

commit 83a0030
Author: ocornut <[email protected]>
Date:   Mon Sep 26 10:33:44 2022 +0200

    Added ImGuiMod_Shortcut which is ImGuiMod_Super on Mac and ImGuiMod_Ctrl otherwise. (ocornut#456)

commit fd408c9
Author: ocornut <[email protected]>
Date:   Thu Sep 22 18:58:33 2022 +0200

    Renamed and merged keyboard modifiers key enums and flags into a same set:. ImGuiKey_ModXXX -> ImGuiMod_XXX and ImGuiModFlags_XXX -> ImGuiMod_XXX. (ocornut#4921, ocornut#456)

    Changed signature of GetKeyChordName() to use ImGuiKeyChord.
    Additionally SetActiveIdUsingAllKeyboardKeys() doesn't set ImGuiKey_ModXXX but we never need/use those and the system will be changed in upcoming commits.

# Conflicts:
#	docs/CHANGELOG.txt
#	imgui.h
#	imgui_demo.cpp
BramblePie pushed a commit to BramblePie/imgui that referenced this pull request Oct 26, 2022
@cfillion @BramblePie
imgui_freetype: Assert if bitmap size exceed chunk size to avoid buff…
30fec48 
…er overflow. (ocornut#5731)
kjblanchard pushed a commit to kjblanchard/imgui that referenced this pull request May 5, 2023
@cfillion @kjblanchard
imgui_freetype: Assert if bitmap size exceed chunk size to avoid buff…
4892c14 
…er overflow. (ocornut#5731)
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@cfillion @ocornut