This is a note to let you know that I've just added the patch titled
io_uring/rsrc: fix null-ptr-deref in io_file_bitmap_get()
to the 6.2-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
io_uring-rsrc-fix-null-ptr-deref-in-io_file_bitmap_get.patch
and it can be found in the queue-6.2 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 02a4d923e4400a36d340ea12d8058f69ebf3a383 Mon Sep 17 00:00:00 2001
From: Savino Dicanosa <sd7.dev@xxxxx>
Date: Tue, 21 Mar 2023 19:44:02 +0000
Subject: io_uring/rsrc: fix null-ptr-deref in io_file_bitmap_get()
From: Savino Dicanosa <sd7.dev@xxxxx>
commit 02a4d923e4400a36d340ea12d8058f69ebf3a383 upstream.
When fixed files are unregistered, file_alloc_end and alloc_hint
are not cleared. This can later cause a NULL pointer dereference in
io_file_bitmap_get() if auto index selection is enabled via
IORING_FILE_INDEX_ALLOC:
[ 6.519129] BUG: kernel NULL pointer dereference, address: 0000000000000000
[...]
[ 6.541468] RIP: 0010:_find_next_zero_bit+0x1a/0x70
[...]
[ 6.560906] Call Trace:
[ 6.561322] <TASK>
[ 6.561672] io_file_bitmap_get+0x38/0x60
[ 6.562281] io_fixed_fd_install+0x63/0xb0
[ 6.562851] ? __pfx_io_socket+0x10/0x10
[ 6.563396] io_socket+0x93/0xf0
[ 6.563855] ? __pfx_io_socket+0x10/0x10
[ 6.564411] io_issue_sqe+0x5b/0x3d0
[ 6.564914] io_submit_sqes+0x1de/0x650
[ 6.565452] __do_sys_io_uring_enter+0x4fc/0xb20
[ 6.566083] ? __do_sys_io_uring_register+0x11e/0xd80
[ 6.566779] do_syscall_64+0x3c/0x90
[ 6.567247] entry_SYSCALL_64_after_hwframe+0x72/0xdc
[...]
To fix the issue, set file alloc range and alloc_hint to zero after
file tables are freed.
Cc: stable@xxxxxxxxxxxxxxx
Fixes: 4278a0deb1f6 ("io_uring: defer alloc_hint update to io_file_bitmap_set()")
Signed-off-by: Savino Dicanosa <sd7.dev@xxxxx>
[axboe: add explicit bitmap == NULL check as well]
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
io_uring/filetable.c | 3 +++
io_uring/rsrc.c | 1 +
2 files changed, 4 insertions(+)
--- a/io_uring/filetable.c
+++ b/io_uring/filetable.c
@@ -19,6 +19,9 @@ static int io_file_bitmap_get(struct io_
unsigned long nr = ctx->file_alloc_end;
int ret;
+ if (!table->bitmap)
+ return -ENFILE;
+
do {
ret = find_next_zero_bit(table->bitmap, nr, table->alloc_hint);
if (ret != nr)
--- a/io_uring/rsrc.c
+++ b/io_uring/rsrc.c
@@ -794,6 +794,7 @@ void __io_sqe_files_unregister(struct io
}
#endif
io_free_file_tables(&ctx->file_table);
+ io_file_table_set_alloc_range(ctx, 0, 0);
io_rsrc_data_free(ctx->file_data);
ctx->file_data = NULL;
ctx->nr_user_files = 0;
Patches currently in stable-queue which might be from sd7.dev@xxxxx are
queue-6.2/io_uring-rsrc-fix-null-ptr-deref-in-io_file_bitmap_get.patch
