From 78004e9a87f240df03e2f73120d291763c32e0a7 Mon Sep 17 00:00:00 2001 From: Ali Ahmet Memis Date: Fri, 21 Aug 2026 01:45:27 +0000 Subject: openrisc: fix arbitrary kernel memory access via or1k_atomic syscall sys_or1k_atomic() (syscall 244 in the "or1k" ABI) takes two user pointers, v1 and v2, and swaps the words they point to in hand-written assembly. l.lwz r29,0(r4) l.lwz r27,0(r5) l.sw 0(r4),r27 l.sw 0(r5),r29 The pointers are not checked with access_ok(). The four memory accesses also have no exception table entries. A caller passes a kernel address as either pointer, and the syscall reads from and writes to it directly. This gives an unprivileged process a kernel read/write primitive. It overwrites kernel data such as the sys_call_table, gaining code execution in kernel context. Check both pointers before entering the critical section. Add fixups for the four memory accesses so faults on valid but unmapped user addresses return -EFAULT. [shorne@gmail.com: fix comment style] Fixes: 9d02a4283e9c ("OpenRISC: Boot code") Cc: stable@vger.kernel.org Signed-off-by: Ali Ahmet Memis Signed-off-by: Stafford Horne --- io_uring/xattr.c | 197 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 197 insertions(+) create mode 100644 io_uring/xattr.c (limited to 'io_uring/xattr.c') diff --git a/io_uring/xattr.c b/io_uring/xattr.c new file mode 100644 index 000000000..5303df3f2 --- /dev/null +++ b/io_uring/xattr.c @@ -0,0 +1,197 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include + +#include "../fs/internal.h" + +#include "io_uring.h" +#include "xattr.h" + +struct io_xattr { + struct file *file; + struct kernel_xattr_ctx ctx; + struct delayed_filename filename; +}; + +void io_xattr_cleanup(struct io_kiocb *req) +{ + struct io_xattr *ix = io_kiocb_to_cmd(req, struct io_xattr); + + dismiss_delayed_filename(&ix->filename); + kfree(ix->ctx.kname); + kvfree(ix->ctx.kvalue); +} + +static void io_xattr_finish(struct io_kiocb *req, int ret) +{ + req->flags &= ~REQ_F_NEED_CLEANUP; + + io_xattr_cleanup(req); + io_req_set_res(req, ret, 0); +} + +static int __io_getxattr_prep(struct io_kiocb *req, + const struct io_uring_sqe *sqe) +{ + struct io_xattr *ix = io_kiocb_to_cmd(req, struct io_xattr); + const char __user *name; + int ret; + + INIT_DELAYED_FILENAME(&ix->filename); + ix->ctx.kvalue = NULL; + name = u64_to_user_ptr(READ_ONCE(sqe->addr)); + ix->ctx.value = u64_to_user_ptr(READ_ONCE(sqe->addr2)); + ix->ctx.size = READ_ONCE(sqe->len); + ix->ctx.flags = READ_ONCE(sqe->xattr_flags); + + if (ix->ctx.flags) + return -EINVAL; + + ix->ctx.kname = kmalloc_obj(*ix->ctx.kname); + if (!ix->ctx.kname) + return -ENOMEM; + + ret = import_xattr_name(ix->ctx.kname, name); + if (ret) { + kfree(ix->ctx.kname); + return ret; + } + + req->flags |= REQ_F_NEED_CLEANUP; + req->flags |= REQ_F_FORCE_ASYNC; + return 0; +} + +int io_fgetxattr_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) +{ + return __io_getxattr_prep(req, sqe); +} + +int io_getxattr_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) +{ + struct io_xattr *ix = io_kiocb_to_cmd(req, struct io_xattr); + const char __user *path; + int ret; + + if (unlikely(req->flags & REQ_F_FIXED_FILE)) + return -EBADF; + + ret = __io_getxattr_prep(req, sqe); + if (ret) + return ret; + + path = u64_to_user_ptr(READ_ONCE(sqe->addr3)); + + return delayed_getname(&ix->filename, path); +} + +int io_fgetxattr(struct io_kiocb *req, unsigned int issue_flags) +{ + struct io_xattr *ix = io_kiocb_to_cmd(req, struct io_xattr); + int ret; + + WARN_ON_ONCE(issue_flags & IO_URING_F_NONBLOCK); + + ret = file_getxattr(req->file, &ix->ctx); + io_xattr_finish(req, ret); + return IOU_COMPLETE; +} + +int io_getxattr(struct io_kiocb *req, unsigned int issue_flags) +{ + struct io_xattr *ix = io_kiocb_to_cmd(req, struct io_xattr); + CLASS(filename_complete_delayed, name)(&ix->filename); + int ret; + + WARN_ON_ONCE(issue_flags & IO_URING_F_NONBLOCK); + + ret = filename_getxattr(AT_FDCWD, name, LOOKUP_FOLLOW, &ix->ctx); + io_xattr_finish(req, ret); + return IOU_COMPLETE; +} + +static int __io_setxattr_prep(struct io_kiocb *req, + const struct io_uring_sqe *sqe) +{ + struct io_xattr *ix = io_kiocb_to_cmd(req, struct io_xattr); + const char __user *name; + int ret; + + INIT_DELAYED_FILENAME(&ix->filename); + name = u64_to_user_ptr(READ_ONCE(sqe->addr)); + ix->ctx.cvalue = u64_to_user_ptr(READ_ONCE(sqe->addr2)); + ix->ctx.kvalue = NULL; + ix->ctx.size = READ_ONCE(sqe->len); + ix->ctx.flags = READ_ONCE(sqe->xattr_flags); + + ix->ctx.kname = kmalloc_obj(*ix->ctx.kname); + if (!ix->ctx.kname) + return -ENOMEM; + + ret = setxattr_copy(name, &ix->ctx); + if (ret) { + kfree(ix->ctx.kname); + return ret; + } + + req->flags |= REQ_F_NEED_CLEANUP; + req->flags |= REQ_F_FORCE_ASYNC; + return 0; +} + +int io_setxattr_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) +{ + struct io_xattr *ix = io_kiocb_to_cmd(req, struct io_xattr); + const char __user *path; + int ret; + + if (unlikely(req->flags & REQ_F_FIXED_FILE)) + return -EBADF; + + ret = __io_setxattr_prep(req, sqe); + if (ret) + return ret; + + path = u64_to_user_ptr(READ_ONCE(sqe->addr3)); + + return delayed_getname(&ix->filename, path); +} + +int io_fsetxattr_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) +{ + return __io_setxattr_prep(req, sqe); +} + +int io_fsetxattr(struct io_kiocb *req, unsigned int issue_flags) +{ + struct io_xattr *ix = io_kiocb_to_cmd(req, struct io_xattr); + int ret; + + WARN_ON_ONCE(issue_flags & IO_URING_F_NONBLOCK); + + ret = file_setxattr(req->file, &ix->ctx); + io_xattr_finish(req, ret); + return IOU_COMPLETE; +} + +int io_setxattr(struct io_kiocb *req, unsigned int issue_flags) +{ + struct io_xattr *ix = io_kiocb_to_cmd(req, struct io_xattr); + CLASS(filename_complete_delayed, name)(&ix->filename); + int ret; + + WARN_ON_ONCE(issue_flags & IO_URING_F_NONBLOCK); + + ret = filename_setxattr(AT_FDCWD, name, LOOKUP_FOLLOW, &ix->ctx); + io_xattr_finish(req, ret); + return IOU_COMPLETE; +} -- cgit v1.3.1