Jann Horn 45d02f79b5 binder: Don't modify VMA bounds in ->mmap handler ... binder_mmap() tries to prevent the creation of overly big binder mappings by silently truncating the size of the VMA to 4MiB. However, this violates the API contract of mmap(). If userspace attempts to create a large binder VMA, and later attempts to unmap that VMA, it will call munmap() on a range beyond the end of the VMA, which may have been allocated to another VMA in the meantime. This can lead to userspace memory corruption. The following sequence of calls leads to a segfault without this commit: int main(void) { int binder_fd = open("/dev/binder", O_RDWR); if (binder_fd == -1) err(1, "open binder"); void *binder_mapping = mmap(NULL, 0x800000UL, PROT_READ, MAP_SHARED, binder_fd, 0); if (binder_mapping == MAP_FAILED) err(1, "mmap binder"); void *data_mapping = mmap(NULL, 0x400000UL, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0); if (data_mapping == MAP_FAILED) err(1, "mmap data"); munmap(binder_mapping, 0x800000UL); *(char*)data_mapping = 1; return 0; } Cc: stable@vger.kernel.org Signed-off-by: Jann Horn <jannh@google.com> Acked-by: Todd Kjos <tkjos@google.com> Acked-by: Christian Brauner <christian.brauner@ubuntu.com> Link: https://lore.kernel.org/r/20191016150119.154756-1-jannh@google.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2019-10-17 05:58:44 -07:00
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binder_alloc_selftest.c	treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 282	2019-06-05 17:36:37 +02:00
binder_alloc.c	binder: Don't modify VMA bounds in ->mmap handler	2019-10-17 05:58:44 -07:00
binder_alloc.h	binder: return errors from buffer copy functions	2019-07-01 08:42:47 +02:00
binder_internal.h	binder: prevent UAF read in print_binder_transaction_log_entry()	2019-10-10 14:39:22 +02:00
binder_trace.h	treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 282	2019-06-05 17:36:37 +02:00
binder.c	binder: Don't modify VMA bounds in ->mmap handler	2019-10-17 05:58:44 -07:00
binderfs.c	binder: Add binder_proc logging to binderfs	2019-09-04 13:31:26 +02:00
Kconfig	binder: add functions to copy to/from binder buffers	2019-02-12 10:43:57 +01:00
Makefile	treewide: Add SPDX license identifier - Makefile/Kconfig	2019-05-21 10:50:46 +02:00