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authorEtienne Carriere <etienne.carriere@linaro.org>2018-04-29 14:22:29 +0200
committerJens Wiklander <jens.wiklander@linaro.org>2018-05-07 11:51:03 +0200
commitab9d3db5b320a052452b9cd035599ee3c84bbee9 (patch)
tree41c4ef6155959ccda3362333a230de20193bce0e /drivers/tee
parenttee: shm: fix use-after-free via temporarily dropped reference (diff)
downloadlinux-ab9d3db5b320a052452b9cd035599ee3c84bbee9.tar.xz
linux-ab9d3db5b320a052452b9cd035599ee3c84bbee9.zip
tee: check shm references are consistent in offset/size
This change prevents userland from referencing TEE shared memory outside the area initially allocated by its owner. Prior this change an application could not reference or access memory it did not own but it could reference memory not explicitly allocated by owner but still allocated to the owner due to the memory allocation granule. Reported-by: Alexandre Jutras <alexandre.jutras@nxp.com> Signed-off-by: Etienne Carriere <etienne.carriere@linaro.org> Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
Diffstat (limited to 'drivers/tee')
-rw-r--r--drivers/tee/tee_core.c11
1 files changed, 11 insertions, 0 deletions
diff --git a/drivers/tee/tee_core.c b/drivers/tee/tee_core.c
index 0124a91c8d71..dd46b758852a 100644
--- a/drivers/tee/tee_core.c
+++ b/drivers/tee/tee_core.c
@@ -238,6 +238,17 @@ static int params_from_user(struct tee_context *ctx, struct tee_param *params,
if (IS_ERR(shm))
return PTR_ERR(shm);
+ /*
+ * Ensure offset + size does not overflow offset
+ * and does not overflow the size of the referred
+ * shared memory object.
+ */
+ if ((ip.a + ip.b) < ip.a ||
+ (ip.a + ip.b) > shm->size) {
+ tee_shm_put(shm);
+ return -EINVAL;
+ }
+
params[n].u.memref.shm_offs = ip.a;
params[n].u.memref.size = ip.b;
params[n].u.memref.shm = shm;