From a90bcb86ae700c12432446c4aa1819e7b8e172ec Mon Sep 17 00:00:00 2001 From: Petar Penkov Date: Tue, 29 Aug 2017 11:20:32 -0700 Subject: [PATCH 1/2] iov_iter: fix page_copy_sane for compound pages Issue is that if the data crosses a page boundary inside a compound page, this check will incorrectly trigger a WARN_ON. To fix this, compute the order using the head of the compound page and adjust the offset to be relative to that head. Fixes: 72e809ed81ed ("iov_iter: sanity checks for copy to/from page primitives") Signed-off-by: Petar Penkov CC: Al Viro CC: Eric Dumazet Signed-off-by: Al Viro --- lib/iov_iter.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/lib/iov_iter.c b/lib/iov_iter.c index 52c8dd6d8e829..1c1c06ddc20a8 100644 --- a/lib/iov_iter.c +++ b/lib/iov_iter.c @@ -687,8 +687,10 @@ EXPORT_SYMBOL(_copy_from_iter_full_nocache); static inline bool page_copy_sane(struct page *page, size_t offset, size_t n) { - size_t v = n + offset; - if (likely(n <= v && v <= (PAGE_SIZE << compound_order(page)))) + struct page *head = compound_head(page); + size_t v = n + offset + page_address(page) - page_address(head); + + if (likely(n <= v && v <= (PAGE_SIZE << compound_order(head)))) return true; WARN_ON(1); return false; From 58aff0af757356065f33290d96a9cd46dfbcae88 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Mon, 18 Sep 2017 17:47:38 +0100 Subject: [PATCH 2/2] ipc/shm: Fix order of parameters when calling copy_compat_shmid_to_user Commit 553f770ef71b ("ipc: move compat shmctl to native") moved the compat IPC syscall handling into ipc/shm.c and refactored the struct accessors in the process. Unfortunately, the call to copy_compat_shmid_to_user when handling a compat {IPC,SHM}_STAT command gets the arguments the wrong way round, passing a kernel stack address as the user buffer (destination) and the user buffer as the kernel stack address (source). This patch fixes the parameter ordering so the buffers are accessed correctly. Cc: Al Viro Cc: Andrew Morton Signed-off-by: Will Deacon Signed-off-by: Al Viro --- ipc/shm.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/ipc/shm.c b/ipc/shm.c index 1b3adfe3c60e2..1e2b1692ba2c6 100644 --- a/ipc/shm.c +++ b/ipc/shm.c @@ -1237,7 +1237,7 @@ COMPAT_SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, void __user *, uptr) err = shmctl_stat(ns, shmid, cmd, &sem64); if (err < 0) return err; - if (copy_compat_shmid_to_user(&sem64, uptr, version)) + if (copy_compat_shmid_to_user(uptr, &sem64, version)) err = -EFAULT; return err;