From 1c47c0d6014c832ad8e2ba04fc2c5b7070d999f7 Mon Sep 17 00:00:00 2001
From: Jens Axboe <axboe@kernel.dk>
Date: Wed, 28 Aug 2024 09:42:33 -0600
Subject: [PATCH] io_uring/rsrc: ensure compat iovecs are copied correctly
For buffer registration (or updates), a userspace iovec is copied in
and updated. If the application is within a compat syscall, then the
iovec type is compat_iovec rather than iovec. However, the type used
in __io_sqe_buffers_update() and io_sqe_buffers_register() is always
struct iovec, and hence the source is incremented by the size of a
non-compat iovec in the loop. This misses every other iovec in the
source, and will run into garbage half way through the copies and
return -EFAULT to the application.
Maintain the source address separately and assign to our user vec
pointer, so that copies always happen from the right source address.
While in there, correct a bad placement of __user which triggered
the following sparse warning prior to this fix:
io_uring/rsrc.c:981:33: warning: cast removes address space '__user' of expression
io_uring/rsrc.c:981:30: warning: incorrect type in assignment (different address spaces)
io_uring/rsrc.c:981:30: expected struct iovec const [noderef] __user *uvec
io_uring/rsrc.c:981:30: got struct iovec *[noderef] __user
Fixes: f4eaf8eda89e ("io_uring/rsrc: Drop io_copy_iov in favor of iovec API")
Reviewed-by: Gabriel Krisman Bertazi <krisman@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
io_uring/rsrc.c | 19 +++++++++++++++----
1 file changed, 15 insertions(+), 4 deletions(-)
diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c
index a860516bf4484..453867add7caa 100644
--- a/io_uring/rsrc.c
+++ b/io_uring/rsrc.c
@@ -394,10 +394,11 @@ static int __io_sqe_buffers_update(struct io_ring_ctx *ctx,
struct io_uring_rsrc_update2 *up,
unsigned int nr_args)
{
- struct iovec __user *uvec = u64_to_user_ptr(up->data);
u64 __user *tags = u64_to_user_ptr(up->tags);
struct iovec fast_iov, *iov;
struct page *last_hpage = NULL;
+ struct iovec __user *uvec;
+ u64 user_data = up->data;
__u32 done;
int i, err;
@@ -410,7 +411,8 @@ static int __io_sqe_buffers_update(struct io_ring_ctx *ctx,
struct io_mapped_ubuf *imu;
u64 tag = 0;
- iov = iovec_from_user(&uvec[done], 1, 1, &fast_iov, ctx->compat);
+ uvec = u64_to_user_ptr(user_data);
+ iov = iovec_from_user(uvec, 1, 1, &fast_iov, ctx->compat);
if (IS_ERR(iov)) {
err = PTR_ERR(iov);
break;
@@ -443,6 +445,10 @@ static int __io_sqe_buffers_update(struct io_ring_ctx *ctx,
ctx->user_bufs[i] = imu;
*io_get_tag_slot(ctx->buf_data, i) = tag;
+ if (ctx->compat)
+ user_data += sizeof(struct compat_iovec);
+ else
+ user_data += sizeof(struct iovec);
}
return done ? done : err;
}
@@ -949,7 +955,7 @@ int io_sqe_buffers_register(struct io_ring_ctx *ctx, void __user *arg,
struct page *last_hpage = NULL;
struct io_rsrc_data *data;
struct iovec fast_iov, *iov = &fast_iov;
- const struct iovec __user *uvec = (struct iovec * __user) arg;
+ const struct iovec __user *uvec;
int i, ret;
BUILD_BUG_ON(IORING_MAX_REG_BUFFERS >= (1u << 16));
@@ -972,7 +978,8 @@ int io_sqe_buffers_register(struct io_ring_ctx *ctx, void __user *arg,
for (i = 0; i < nr_args; i++, ctx->nr_user_bufs++) {
if (arg) {
- iov = iovec_from_user(&uvec[i], 1, 1, &fast_iov, ctx->compat);
+ uvec = (struct iovec __user *) arg;
+ iov = iovec_from_user(uvec, 1, 1, &fast_iov, ctx->compat);
if (IS_ERR(iov)) {
ret = PTR_ERR(iov);
break;
@@ -980,6 +987,10 @@ int io_sqe_buffers_register(struct io_ring_ctx *ctx, void __user *arg,
ret = io_buffer_validate(iov);
if (ret)
break;
+ if (ctx->compat)
+ arg += sizeof(struct compat_iovec);
+ else
+ arg += sizeof(struct iovec);
}
if (!iov->iov_base && *io_get_tag_slot(data, i)) {
--
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