tree 3847c9f199e1508bd9dcb93bcced2267eb6e393c
parent d3e1f54508f1cc2a0d82f37cb2b301b7dcc4f5bb
author Haimin Zhang <tcs.kernel@gmail.com> 1639566930 +0800
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1640161855 +0100

netdevsim: Zero-initialize memory for new map's value in function nsim_bpf_map_alloc

[ Upstream commit 481221775d53d6215a6e5e9ce1cce6d2b4ab9a46 ]

Zero-initialize memory for new map's value in function nsim_bpf_map_alloc
since it may cause a potential kernel information leak issue, as follows:
1. nsim_bpf_map_alloc calls nsim_map_alloc_elem to allocate elements for
a new map.
2. nsim_map_alloc_elem uses kmalloc to allocate map's value, but doesn't
zero it.
3. A user application can use IOCTL BPF_MAP_LOOKUP_ELEM to get specific
element's information in the map.
4. The kernel function map_lookup_elem will call bpf_map_copy_value to get
the information allocated at step-2, then use copy_to_user to copy to the
user buffer.
This can only leak information for an array map.

Fixes: 395cacb5f1a0 ("netdevsim: bpf: support fake map offload")
Suggested-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Haimin Zhang <tcs.kernel@gmail.com>
Link: https://lore.kernel.org/r/20211215111530.72103-1-tcs.kernel@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>