2022-08-06 14:53:30

by Jialiang Wang

[permalink] [raw]
Subject: [PATCH] nfp: fix use-after-free in area_cache_get()

area_cache_get() calls cpp->op->area_init() and uses cache->area by
nfp_cpp_area_priv(area), but in
nfp_cpp_area_release()->nfp_cpp_area_put()->__release_cpp_area() we
already freed the cache->area.

To avoid the use-after-free, reallocate a piece of memory for the
cache->area by nfp_cpp_area_alloc().

Note: This vulnerability is triggerable by providing emulated device
equipped with specified configuration.

BUG: KASAN: use-after-free in nfp6000_area_init+0x74/0x1d0 [nfp]
Write of size 4 at addr ffff888005b490a0 by task insmod/226
Call Trace:
<TASK>
dump_stack_lvl+0x33/0x46
print_report.cold.12+0xb2/0x6b7
? nfp6000_area_init+0x74/0x1d0 [nfp]
kasan_report+0xa5/0x120
? nfp6000_area_init+0x74/0x1d0 [nfp]
nfp6000_area_init+0x74/0x1d0 [nfp]
area_cache_get.constprop.8+0x2da/0x360 [nfp]

Signed-off-by: Jialiang Wang <[email protected]>
---
drivers/net/ethernet/netronome/nfp/nfpcore/nfp_cppcore.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_cppcore.c b/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_cppcore.c
index 34c0d2ddf9ef..99091f24d2ba 100644
--- a/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_cppcore.c
+++ b/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_cppcore.c
@@ -871,6 +871,10 @@ area_cache_get(struct nfp_cpp *cpp, u32 id,
nfp_cpp_area_release(cache->area);
cache->id = 0;
cache->addr = 0;
+ cache->area = nfp_cpp_area_alloc(cpp,
+ NFP_CPP_ID(7,
+ NFP_CPP_ACTION_RW, 0),
+ 0, cache->size);
}

/* Adjust the start address to be cache size aligned */
--
2.17.1