From: Todd Kjos tkjos@android.com
commit bb4a2e48d5100ed3ff614df158a636bca3c6bf9f upstream.
The buffer copy functions assumed the caller would ensure correct alignment and that the memory to be copied was completely within the binder buffer. There have been a few cases discovered by syzkallar where a malformed transaction created by a user could violated the assumptions and resulted in a BUG_ON.
The fix is to remove the BUG_ON and always return the error to be handled appropriately by the caller.
Acked-by: Martijn Coenen maco@android.com Reported-by: syzbot+3ae18325f96190606754@syzkaller.appspotmail.com Fixes: bde4a19fc04f ("binder: use userspace pointer as base of buffer space") Suggested-by: Dan Carpenter dan.carpenter@oracle.com Signed-off-by: Todd Kjos tkjos@google.com Cc: stable stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/android/binder.c | 151 ++++++++++++++++++++++++----------------- drivers/android/binder_alloc.c | 44 ++++++----- drivers/android/binder_alloc.h | 20 ++--- 3 files changed, 124 insertions(+), 91 deletions(-)
--- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -2068,10 +2068,9 @@ static size_t binder_get_object(struct b
read_size = min_t(size_t, sizeof(*object), buffer->data_size - offset); if (offset > buffer->data_size || read_size < sizeof(*hdr) || - !IS_ALIGNED(offset, sizeof(u32))) + binder_alloc_copy_from_buffer(&proc->alloc, object, buffer, + offset, read_size)) return 0; - binder_alloc_copy_from_buffer(&proc->alloc, object, buffer, - offset, read_size);
/* Ok, now see if we read a complete object. */ hdr = &object->hdr; @@ -2140,8 +2139,10 @@ static struct binder_buffer_object *bind return NULL;
buffer_offset = start_offset + sizeof(binder_size_t) * index; - binder_alloc_copy_from_buffer(&proc->alloc, &object_offset, - b, buffer_offset, sizeof(object_offset)); + if (binder_alloc_copy_from_buffer(&proc->alloc, &object_offset, + b, buffer_offset, + sizeof(object_offset))) + return NULL; object_size = binder_get_object(proc, b, object_offset, object); if (!object_size || object->hdr.type != BINDER_TYPE_PTR) return NULL; @@ -2221,10 +2222,12 @@ static bool binder_validate_fixup(struct return false; last_min_offset = last_bbo->parent_offset + sizeof(uintptr_t); buffer_offset = objects_start_offset + - sizeof(binder_size_t) * last_bbo->parent, - binder_alloc_copy_from_buffer(&proc->alloc, &last_obj_offset, - b, buffer_offset, - sizeof(last_obj_offset)); + sizeof(binder_size_t) * last_bbo->parent; + if (binder_alloc_copy_from_buffer(&proc->alloc, + &last_obj_offset, + b, buffer_offset, + sizeof(last_obj_offset))) + return false; } return (fixup_offset >= last_min_offset); } @@ -2310,15 +2313,15 @@ static void binder_transaction_buffer_re for (buffer_offset = off_start_offset; buffer_offset < off_end_offset; buffer_offset += sizeof(binder_size_t)) { struct binder_object_header *hdr; - size_t object_size; + size_t object_size = 0; struct binder_object object; binder_size_t object_offset;
- binder_alloc_copy_from_buffer(&proc->alloc, &object_offset, - buffer, buffer_offset, - sizeof(object_offset)); - object_size = binder_get_object(proc, buffer, - object_offset, &object); + if (!binder_alloc_copy_from_buffer(&proc->alloc, &object_offset, + buffer, buffer_offset, + sizeof(object_offset))) + object_size = binder_get_object(proc, buffer, + object_offset, &object); if (object_size == 0) { pr_err("transaction release %d bad object at offset %lld, size %zd\n", debug_id, (u64)object_offset, buffer->data_size); @@ -2441,15 +2444,16 @@ static void binder_transaction_buffer_re for (fd_index = 0; fd_index < fda->num_fds; fd_index++) { u32 fd; + int err; binder_size_t offset = fda_offset + fd_index * sizeof(fd);
- binder_alloc_copy_from_buffer(&proc->alloc, - &fd, - buffer, - offset, - sizeof(fd)); - binder_deferred_fd_close(fd); + err = binder_alloc_copy_from_buffer( + &proc->alloc, &fd, buffer, + offset, sizeof(fd)); + WARN_ON(err); + if (!err) + binder_deferred_fd_close(fd); } } break; default: @@ -2692,11 +2696,12 @@ static int binder_translate_fd_array(str int ret; binder_size_t offset = fda_offset + fdi * sizeof(fd);
- binder_alloc_copy_from_buffer(&target_proc->alloc, - &fd, t->buffer, - offset, sizeof(fd)); - ret = binder_translate_fd(fd, offset, t, thread, - in_reply_to); + ret = binder_alloc_copy_from_buffer(&target_proc->alloc, + &fd, t->buffer, + offset, sizeof(fd)); + if (!ret) + ret = binder_translate_fd(fd, offset, t, thread, + in_reply_to); if (ret < 0) return ret; } @@ -2749,8 +2754,12 @@ static int binder_fixup_parent(struct bi } buffer_offset = bp->parent_offset + (uintptr_t)parent->buffer - (uintptr_t)b->user_data; - binder_alloc_copy_to_buffer(&target_proc->alloc, b, buffer_offset, - &bp->buffer, sizeof(bp->buffer)); + if (binder_alloc_copy_to_buffer(&target_proc->alloc, b, buffer_offset, + &bp->buffer, sizeof(bp->buffer))) { + binder_user_error("%d:%d got transaction with invalid parent offset\n", + proc->pid, thread->pid); + return -EINVAL; + }
return 0; } @@ -3160,15 +3169,20 @@ static void binder_transaction(struct bi goto err_binder_alloc_buf_failed; } if (secctx) { + int err; size_t buf_offset = ALIGN(tr->data_size, sizeof(void *)) + ALIGN(tr->offsets_size, sizeof(void *)) + ALIGN(extra_buffers_size, sizeof(void *)) - ALIGN(secctx_sz, sizeof(u64));
t->security_ctx = (uintptr_t)t->buffer->user_data + buf_offset; - binder_alloc_copy_to_buffer(&target_proc->alloc, - t->buffer, buf_offset, - secctx, secctx_sz); + err = binder_alloc_copy_to_buffer(&target_proc->alloc, + t->buffer, buf_offset, + secctx, secctx_sz); + if (err) { + t->security_ctx = 0; + WARN_ON(1); + } security_release_secctx(secctx, secctx_sz); secctx = NULL; } @@ -3234,11 +3248,16 @@ static void binder_transaction(struct bi struct binder_object object; binder_size_t object_offset;
- binder_alloc_copy_from_buffer(&target_proc->alloc, - &object_offset, - t->buffer, - buffer_offset, - sizeof(object_offset)); + if (binder_alloc_copy_from_buffer(&target_proc->alloc, + &object_offset, + t->buffer, + buffer_offset, + sizeof(object_offset))) { + return_error = BR_FAILED_REPLY; + return_error_param = -EINVAL; + return_error_line = __LINE__; + goto err_bad_offset; + } object_size = binder_get_object(target_proc, t->buffer, object_offset, &object); if (object_size == 0 || object_offset < off_min) { @@ -3262,15 +3281,17 @@ static void binder_transaction(struct bi
fp = to_flat_binder_object(hdr); ret = binder_translate_binder(fp, t, thread); - if (ret < 0) { + + if (ret < 0 || + binder_alloc_copy_to_buffer(&target_proc->alloc, + t->buffer, + object_offset, + fp, sizeof(*fp))) { return_error = BR_FAILED_REPLY; return_error_param = ret; return_error_line = __LINE__; goto err_translate_failed; } - binder_alloc_copy_to_buffer(&target_proc->alloc, - t->buffer, object_offset, - fp, sizeof(*fp)); } break; case BINDER_TYPE_HANDLE: case BINDER_TYPE_WEAK_HANDLE: { @@ -3278,15 +3299,16 @@ static void binder_transaction(struct bi
fp = to_flat_binder_object(hdr); ret = binder_translate_handle(fp, t, thread); - if (ret < 0) { + if (ret < 0 || + binder_alloc_copy_to_buffer(&target_proc->alloc, + t->buffer, + object_offset, + fp, sizeof(*fp))) { return_error = BR_FAILED_REPLY; return_error_param = ret; return_error_line = __LINE__; goto err_translate_failed; } - binder_alloc_copy_to_buffer(&target_proc->alloc, - t->buffer, object_offset, - fp, sizeof(*fp)); } break;
case BINDER_TYPE_FD: { @@ -3296,16 +3318,17 @@ static void binder_transaction(struct bi int ret = binder_translate_fd(fp->fd, fd_offset, t, thread, in_reply_to);
- if (ret < 0) { + fp->pad_binder = 0; + if (ret < 0 || + binder_alloc_copy_to_buffer(&target_proc->alloc, + t->buffer, + object_offset, + fp, sizeof(*fp))) { return_error = BR_FAILED_REPLY; return_error_param = ret; return_error_line = __LINE__; goto err_translate_failed; } - fp->pad_binder = 0; - binder_alloc_copy_to_buffer(&target_proc->alloc, - t->buffer, object_offset, - fp, sizeof(*fp)); } break; case BINDER_TYPE_FDA: { struct binder_object ptr_object; @@ -3393,15 +3416,16 @@ static void binder_transaction(struct bi num_valid, last_fixup_obj_off, last_fixup_min_off); - if (ret < 0) { + if (ret < 0 || + binder_alloc_copy_to_buffer(&target_proc->alloc, + t->buffer, + object_offset, + bp, sizeof(*bp))) { return_error = BR_FAILED_REPLY; return_error_param = ret; return_error_line = __LINE__; goto err_translate_failed; } - binder_alloc_copy_to_buffer(&target_proc->alloc, - t->buffer, object_offset, - bp, sizeof(*bp)); last_fixup_obj_off = object_offset; last_fixup_min_off = 0; } break; @@ -4139,20 +4163,27 @@ static int binder_apply_fd_fixups(struct trace_binder_transaction_fd_recv(t, fd, fixup->offset); fd_install(fd, fixup->file); fixup->file = NULL; - binder_alloc_copy_to_buffer(&proc->alloc, t->buffer, - fixup->offset, &fd, - sizeof(u32)); + if (binder_alloc_copy_to_buffer(&proc->alloc, t->buffer, + fixup->offset, &fd, + sizeof(u32))) { + ret = -EINVAL; + break; + } } list_for_each_entry_safe(fixup, tmp, &t->fd_fixups, fixup_entry) { if (fixup->file) { fput(fixup->file); } else if (ret) { u32 fd; + int err;
- binder_alloc_copy_from_buffer(&proc->alloc, &fd, - t->buffer, fixup->offset, - sizeof(fd)); - binder_deferred_fd_close(fd); + err = binder_alloc_copy_from_buffer(&proc->alloc, &fd, + t->buffer, + fixup->offset, + sizeof(fd)); + WARN_ON(err); + if (!err) + binder_deferred_fd_close(fd); } list_del(&fixup->fixup_entry); kfree(fixup); --- a/drivers/android/binder_alloc.c +++ b/drivers/android/binder_alloc.c @@ -1128,15 +1128,16 @@ binder_alloc_copy_user_to_buffer(struct return 0; }
-static void binder_alloc_do_buffer_copy(struct binder_alloc *alloc, - bool to_buffer, - struct binder_buffer *buffer, - binder_size_t buffer_offset, - void *ptr, - size_t bytes) +static int binder_alloc_do_buffer_copy(struct binder_alloc *alloc, + bool to_buffer, + struct binder_buffer *buffer, + binder_size_t buffer_offset, + void *ptr, + size_t bytes) { /* All copies must be 32-bit aligned and 32-bit size */ - BUG_ON(!check_buffer(alloc, buffer, buffer_offset, bytes)); + if (!check_buffer(alloc, buffer, buffer_offset, bytes)) + return -EINVAL;
while (bytes) { unsigned long size; @@ -1164,25 +1165,26 @@ static void binder_alloc_do_buffer_copy( ptr = ptr + size; buffer_offset += size; } + return 0; }
-void binder_alloc_copy_to_buffer(struct binder_alloc *alloc, - struct binder_buffer *buffer, - binder_size_t buffer_offset, - void *src, - size_t bytes) +int binder_alloc_copy_to_buffer(struct binder_alloc *alloc, + struct binder_buffer *buffer, + binder_size_t buffer_offset, + void *src, + size_t bytes) { - binder_alloc_do_buffer_copy(alloc, true, buffer, buffer_offset, - src, bytes); + return binder_alloc_do_buffer_copy(alloc, true, buffer, buffer_offset, + src, bytes); }
-void binder_alloc_copy_from_buffer(struct binder_alloc *alloc, - void *dest, - struct binder_buffer *buffer, - binder_size_t buffer_offset, - size_t bytes) +int binder_alloc_copy_from_buffer(struct binder_alloc *alloc, + void *dest, + struct binder_buffer *buffer, + binder_size_t buffer_offset, + size_t bytes) { - binder_alloc_do_buffer_copy(alloc, false, buffer, buffer_offset, - dest, bytes); + return binder_alloc_do_buffer_copy(alloc, false, buffer, buffer_offset, + dest, bytes); }
--- a/drivers/android/binder_alloc.h +++ b/drivers/android/binder_alloc.h @@ -168,17 +168,17 @@ binder_alloc_copy_user_to_buffer(struct const void __user *from, size_t bytes);
-void binder_alloc_copy_to_buffer(struct binder_alloc *alloc, - struct binder_buffer *buffer, - binder_size_t buffer_offset, - void *src, - size_t bytes); +int binder_alloc_copy_to_buffer(struct binder_alloc *alloc, + struct binder_buffer *buffer, + binder_size_t buffer_offset, + void *src, + size_t bytes);
-void binder_alloc_copy_from_buffer(struct binder_alloc *alloc, - void *dest, - struct binder_buffer *buffer, - binder_size_t buffer_offset, - size_t bytes); +int binder_alloc_copy_from_buffer(struct binder_alloc *alloc, + void *dest, + struct binder_buffer *buffer, + binder_size_t buffer_offset, + size_t bytes);
#endif /* _LINUX_BINDER_ALLOC_H */