diff options
author | Willy Tarreau <w@1wt.eu> | 2022-05-08 12:37:07 +0300 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-05-25 10:17:51 +0300 |
commit | 911b36267855501f7f80a75927c128c0ac03fe58 (patch) | |
tree | ba8e2a45d9d8b8458c43441977e752f3519f0e6e /drivers/block | |
parent | 3c48558be571e01f67e65edcf03193484eeb2b79 (diff) | |
download | linux-911b36267855501f7f80a75927c128c0ac03fe58.tar.xz |
floppy: use a statically allocated error counter
commit f71f01394f742fc4558b3f9f4c7ef4c4cf3b07c8 upstream.
Interrupt handler bad_flp_intr() may cause a UAF on the recently freed
request just to increment the error count. There's no point keeping
that one in the request anyway, and since the interrupt handler uses a
static pointer to the error which cannot be kept in sync with the
pending request, better make it use a static error counter that's reset
for each new request. This reset now happens when entering
redo_fd_request() for a new request via set_next_request().
One initial concern about a single error counter was that errors on one
floppy drive could be reported on another one, but this problem is not
real given that the driver uses a single drive at a time, as that
PC-compatible controllers also have this limitation by using shared
signals. As such the error count is always for the "current" drive.
Reported-by: Minh Yuan <yuanmingbuaa@gmail.com>
Suggested-by: Linus Torvalds <torvalds@linuxfoundation.org>
Tested-by: Denis Efremov <efremov@linux.com>
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Denis Efremov <efremov@linux.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/block')
-rw-r--r-- | drivers/block/floppy.c | 20 |
1 files changed, 9 insertions, 11 deletions
diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c index c9411fe2f0af..4ef407a33996 100644 --- a/drivers/block/floppy.c +++ b/drivers/block/floppy.c @@ -509,8 +509,8 @@ static unsigned long fdc_busy; static DECLARE_WAIT_QUEUE_HEAD(fdc_wait); static DECLARE_WAIT_QUEUE_HEAD(command_done); -/* Errors during formatting are counted here. */ -static int format_errors; +/* errors encountered on the current (or last) request */ +static int floppy_errors; /* Format request descriptor. */ static struct format_descr format_req; @@ -530,7 +530,6 @@ static struct format_descr format_req; static char *floppy_track_buffer; static int max_buffer_sectors; -static int *errors; typedef void (*done_f)(int); static const struct cont_t { void (*interrupt)(void); @@ -1455,7 +1454,7 @@ static int interpret_errors(void) if (drive_params[current_drive].flags & FTD_MSG) DPRINT("Over/Underrun - retrying\n"); bad = 0; - } else if (*errors >= drive_params[current_drive].max_errors.reporting) { + } else if (floppy_errors >= drive_params[current_drive].max_errors.reporting) { print_errors(); } if (reply_buffer[ST2] & ST2_WC || reply_buffer[ST2] & ST2_BC) @@ -2095,7 +2094,7 @@ static void bad_flp_intr(void) if (!next_valid_format(current_drive)) return; } - err_count = ++(*errors); + err_count = ++floppy_errors; INFBOUND(write_errors[current_drive].badness, err_count); if (err_count > drive_params[current_drive].max_errors.abort) cont->done(0); @@ -2240,9 +2239,8 @@ static int do_format(int drive, struct format_descr *tmp_format_req) return -EINVAL; } format_req = *tmp_format_req; - format_errors = 0; cont = &format_cont; - errors = &format_errors; + floppy_errors = 0; ret = wait_til_done(redo_format, true); if (ret == -EINTR) return -EINTR; @@ -2721,7 +2719,7 @@ static int make_raw_rw_request(void) */ if (!direct || (indirect * 2 > direct * 3 && - *errors < drive_params[current_drive].max_errors.read_track && + floppy_errors < drive_params[current_drive].max_errors.read_track && ((!probing || (drive_params[current_drive].read_track & (1 << drive_state[current_drive].probed_format)))))) { max_size = blk_rq_sectors(current_req); @@ -2846,10 +2844,11 @@ static int set_next_request(void) current_req = list_first_entry_or_null(&floppy_reqs, struct request, queuelist); if (current_req) { - current_req->error_count = 0; + floppy_errors = 0; list_del_init(¤t_req->queuelist); + return 1; } - return current_req != NULL; + return 0; } /* Starts or continues processing request. Will automatically unlock the @@ -2908,7 +2907,6 @@ do_request: _floppy = floppy_type + drive_params[current_drive].autodetect[drive_state[current_drive].probed_format]; } else probing = 0; - errors = &(current_req->error_count); tmp = make_raw_rw_request(); if (tmp < 2) { request_done(tmp); |