forked from mirrors/linux
12d908116f
Currently, io_uring_unreg_ringfd() (which cleans up registered rings) is
only called on exit, but __io_uring_free (which frees the tctx in which the
registered ring pointers are stored) is also called on execve (via
begin_new_exec -> io_uring_task_cancel -> __io_uring_cancel ->
io_uring_cancel_generic -> __io_uring_free).
This means: A process going through execve while having registered rings
will leak references to the rings' `struct file`.
Fix it by zapping registered rings on execve(). This is implemented by
moving the io_uring_unreg_ringfd() from io_uring_files_cancel() into its
callee __io_uring_cancel(), which is called from io_uring_task_cancel() on
execve.
This could probably be exploited *on 32-bit kernels* by leaking 2^32
references to the same ring, because the file refcount is stored in a
pointer-sized field and get_file() doesn't have protection against
refcount overflow, just a WARN_ONCE(); but on 64-bit it should have no
impact beyond a memory leak.
Cc: stable@vger.kernel.org
Fixes: e7a6c00dc7 ("io_uring: add support for registering ring file descriptors")
Signed-off-by: Jann Horn <jannh@google.com>
Link: https://lore.kernel.org/r/20241218-uring-reg-ring-cleanup-v1-1-8f63e999045b@google.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
51 lines
1 KiB
C
51 lines
1 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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#ifndef _LINUX_IO_URING_H
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#define _LINUX_IO_URING_H
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#include <linux/sched.h>
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#include <linux/xarray.h>
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#include <uapi/linux/io_uring.h>
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#if defined(CONFIG_IO_URING)
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void __io_uring_cancel(bool cancel_all);
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void __io_uring_free(struct task_struct *tsk);
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void io_uring_unreg_ringfd(void);
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const char *io_uring_get_opcode(u8 opcode);
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bool io_is_uring_fops(struct file *file);
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static inline void io_uring_files_cancel(void)
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{
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if (current->io_uring)
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__io_uring_cancel(false);
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}
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static inline void io_uring_task_cancel(void)
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{
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if (current->io_uring)
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__io_uring_cancel(true);
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}
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static inline void io_uring_free(struct task_struct *tsk)
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{
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if (tsk->io_uring)
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__io_uring_free(tsk);
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}
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#else
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static inline void io_uring_task_cancel(void)
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{
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}
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static inline void io_uring_files_cancel(void)
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{
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}
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static inline void io_uring_free(struct task_struct *tsk)
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{
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}
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static inline const char *io_uring_get_opcode(u8 opcode)
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{
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return "";
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}
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static inline bool io_is_uring_fops(struct file *file)
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{
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return false;
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}
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#endif
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#endif
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