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author | Thadeu Lima de Souza Cascardo <cascardo@igalia.com> | 2025-03-17 16:59:55 +0300 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-04-15 17:22:15 +0300 |
commit | c876be906ce7e518d9ef9926478669c151999e69 (patch) | |
tree | dec9006a9018c15c98858eeb30d5122cba689272 | |
parent | 86ce5c0a1dec02e21b4c864b2bc0cc5880a2c13c (diff) | |
download | linux-c876be906ce7e518d9ef9926478669c151999e69.tar.xz |
char: misc: register chrdev region with all possible minors
register_chrdev will only register the first 256 minors of a major chrdev.
That means that dynamically allocated misc devices with minor above 255
will fail to open with -ENXIO.
This was found by kernel test robot when testing a different change that
makes all dynamically allocated minors be above 255. This has, however,
been separately tested by creating 256 serio_raw devices with the help of
userio driver.
Ever since allowing misc devices with minors above 128, this has been
possible.
Fix it by registering all minor numbers from 0 to MINORMASK + 1 for
MISC_MAJOR.
Reported-by: kernel test robot <oliver.sang@intel.com>
Cc: stable <stable@kernel.org>
Closes: https://lore.kernel.org/oe-lkp/202503171507.6c8093d0-lkp@intel.com
Fixes: ab760791c0cf ("char: misc: Increase the maximum number of dynamic misc devices to 1048448")
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@igalia.com>
Tested-by: Hou Wenlong <houwenlong.hwl@antgroup.com>
Link: https://lore.kernel.org/r/20250317-misc-chrdev-v1-1-6cd05da11aef@igalia.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r-- | drivers/char/misc.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/char/misc.c b/drivers/char/misc.c index f7dd455dd0dd..dda466f9181a 100644 --- a/drivers/char/misc.c +++ b/drivers/char/misc.c @@ -315,7 +315,7 @@ static int __init misc_init(void) goto fail_remove; err = -EIO; - if (register_chrdev(MISC_MAJOR, "misc", &misc_fops)) + if (__register_chrdev(MISC_MAJOR, 0, MINORMASK + 1, "misc", &misc_fops)) goto fail_printk; return 0; |