From: Cong Wang Date: Fri, 1 Jun 2018 18:31:44 +0000 (-0700) Subject: infiniband: fix a possible use-after-free bug X-Git-Tag: v4.1.12-124.31.3~490 X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=077770ba0c266b52bfba798fb39c47a5edec8322;p=users%2Fjedix%2Flinux-maple.git infiniband: fix a possible use-after-free bug ucma_process_join() will free the new allocated "mc" struct, if there is any error after that, especially the copy_to_user(). But in parallel, ucma_leave_multicast() could find this "mc" through idr_find() before ucma_process_join() frees it, since it is already published. So "mc" could be used in ucma_leave_multicast() after it is been allocated and freed in ucma_process_join(), since we don't refcnt it. Fix this by separating "publish" from ID allocation, so that we can get an ID first and publish it later after copy_to_user(). Fixes: c8f6a362bf3e ("RDMA/cma: Add multicast communication support") Reported-by: Noam Rathaus Signed-off-by: Cong Wang Signed-off-by: Jason Gunthorpe (cherry picked from commit cb2595c1393b4a5211534e6f0a0fbad369e21ad8) Orabug: 28774517 CVE: CVE-2018-14734 Reviewed-by: Håkon Bugge Reviewed-by: Darren Kenny Signed-off-by: Allen Pais Signed-off-by: Brian Maly --- diff --git a/drivers/infiniband/core/ucma.c b/drivers/infiniband/core/ucma.c index 81dd84d0b68b..eaadd636c21b 100644 --- a/drivers/infiniband/core/ucma.c +++ b/drivers/infiniband/core/ucma.c @@ -180,7 +180,7 @@ static struct ucma_multicast* ucma_alloc_multicast(struct ucma_context *ctx) return NULL; mutex_lock(&mut); - mc->id = idr_alloc(&multicast_idr, mc, 0, 0, GFP_KERNEL); + mc->id = idr_alloc(&multicast_idr, NULL, 0, 0, GFP_KERNEL); mutex_unlock(&mut); if (mc->id < 0) goto error; @@ -1262,6 +1262,10 @@ static ssize_t ucma_process_join(struct ucma_file *file, goto err3; } + mutex_lock(&mut); + idr_replace(&multicast_idr, mc, mc->id); + mutex_unlock(&mut); + mutex_unlock(&file->mut); ucma_put_ctx(ctx); return 0;