Date: Thu, 21 Apr 2011 18:01:31 +0400 From: Vasiliy Kulikov <segoon@...nwall.com> To: oss-security@...ts.openwall.com Subject: CVE request: kernel: buffer overflow and DoS issues in agp Hi, https://lkml.org/lkml/2011/4/14/293 "pg_start is copied from userspace on AGPIOC_BIND and AGPIOC_UNBIND ioctl cmds of agp_ioctl() and passed to agpioc_bind_wrap(). As said in the comment, (pg_start + mem->page_count) may wrap in case of AGPIOC_BIND, and it is not checked at all in case of AGPIOC_UNBIND. As a result, user with sufficient privileges (usually "video" group) may generate either local DoS or privilege escalation." https://lkml.org/lkml/2011/4/14/294 https://lkml.org/lkml/2011/4/19/400 "page_count is copied from userspace. agp_allocate_memory() tries to check whether this number is too big, but doesn't take into account the wrap case. Also agp_create_user_memory() doesn't check whether alloc_size is calculated from num_agp_pages variable without overflow. This may lead to allocation of too small buffer with following buffer overflow. Another problem in agp code is not addressed in the patch - kernel memory exhaustion (AGPIOC_RESERVE and AGPIOC_ALLOCATE ioctls). It is not checked whether requested pid is a pid of the caller (no check in agpioc_reserve_wrap()). Each allocation is limited to 16KB, though, there is no per-process limit. This might lead to OOM situation, which is not even solved in case of the caller death by OOM killer - the memory is allocated for another (faked) process." -- Vasiliy Kulikov http://www.openwall.com - bringing security into open computing environments Download attachment "signature.asc" of type "application/pgp-signature" (837 bytes)
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