Bug 1920458 (CVE-2020-14410)

Summary:	CVE-2020-14410 SDL2: Heap-based buffer over-read in Blit_3or4_to_3or4__inversed_rgb in video/SDL_blit_N.c via a crafted .BMP file
Product:	[Other] Security Response	Reporter:	Marian Rehak <mrehak>
Component:	vulnerability	Assignee:	Nobody <nobody>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	dchen, erik-fedora, klember, maci, manisandro, ppisar, spotrh, wtaymans
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	SDL 2.0.14	Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	1920459, 1921873, 1921874, 1921876, 1921877
Bug Blocks:	1920460

Description Marian Rehak 2021-01-26 11:10:38 UTC

SDL (Simple DirectMedia Layer) through 2.0.12 has a heap-based buffer over-read in Blit_3or4_to_3or4__inversed_rgb in video/SDL_blit_N.c via a crafted .BMP file.

Reference:

https://bugzilla.libsdl.org/show_bug.cgi?id=5200

Comment 1 Marian Rehak 2021-01-26 11:11:31 UTC

Created SDL tracking bugs for this issue:

Affects: fedora-all [bug 1920459]

Comment 2 Petr Pisar 2021-01-26 12:47:49 UTC

Didn't you mistaken SDL with SDL2?

The linked patch is for SDL2 and it makes sure that calculating int surface->pitch in SDL_CreateRGBSurfaceWithFormat() does not overflow and thus that any subsequent memory allocation and access based on the pitch and surface->width and surface->height are correct.

SDL we have in Fedora and RHEL and upstream has is already hardened: SDL_CreateRGBSurface() makes sure that width and height fits into unsigned 16-bit integer and SDL_CalculatePitch() makes sure that the pitch computation also fits into unsigned 16-bit integer (surface-pitch is Uint16 type there). The multiplication at SDL_malloc(surface->h*surface->pitch) in SDL_CreateRGBSurface() cannot overflow because the argument has size_t type which is not shorter than unsigned 32-bit on any Fedora and RHEL supported platform. Therefore I think SDL is not vulnerable.

Do you have a counter example? Or at least reproducer for the original SDL2 bug?

Comment 3 Todd Cullum 2021-01-28 18:35:08 UTC

Upstream patch: https://hg.libsdl.org/SDL/rev/3f9b4e92c1d9

Comment 4 Todd Cullum 2021-01-28 18:37:49 UTC

Created SDL2 tracking bugs for this issue:

Affects: fedora-all [bug 1921873]


Created mingw-SDL2 tracking bugs for this issue:

Affects: fedora-all [bug 1921874]

Comment 7 Todd Cullum 2021-01-29 19:32:07 UTC

Statement:

SDL as shipped in Red Hat Enterprise Linux 6, 7, and 8 is not affected as the vulnerable code exists in SDL2; SDL is already hardened for this flaw.