This is a note to let you know that I've just added the patch titled fs: fix fd table size alignment properly to the 5.15-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: fs-fix-fd-table-size-alignment-properly.patch and it can be found in the queue-5.15 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 6b92732dc9151c1eb5c29e6ffe6f68d396657864 Author: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Date: Tue Mar 29 23:29:18 2022 -0700 fs: fix fd table size alignment properly [ Upstream commit d888c83fcec75194a8a48ccd283953bdba7b2550 ] Jason Donenfeld reports that my commit 1c24a186398f ("fs: fd tables have to be multiples of BITS_PER_LONG") doesn't work, and the reason is an embarrassing brown-paper-bag bug. Yes, we want to align the number of fds to BITS_PER_LONG, and yes, the reason they might not be aligned is because the incoming 'max_fd' argument might not be aligned. But aligining the argument - while simple - will cause a "infinitely big" maxfd (eg NR_OPEN_MAX) to just overflow to zero. Which most definitely isn't what we want either. The obvious fix was always just to do the alignment last, but I had moved it earlier just to make the patch smaller and the code look simpler. Duh. It certainly made _me_ look simple. Fixes: 1c24a186398f ("fs: fd tables have to be multiples of BITS_PER_LONG") Reported-and-tested-by: Jason A. Donenfeld <Jason@xxxxxxxxx> Cc: Fedor Pchelkin <aissur0002@xxxxxxxxx> Cc: Alexey Khoroshilov <khoroshilov@xxxxxxxxx> Cc: Christian Brauner <brauner@xxxxxxxxxx> Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/fs/file.c b/fs/file.c index c01c29417ae6..ee9317346702 100644 --- a/fs/file.c +++ b/fs/file.c @@ -303,10 +303,9 @@ static unsigned int sane_fdtable_size(struct fdtable *fdt, unsigned int max_fds) unsigned int count; count = count_open_files(fdt); - max_fds = ALIGN(max_fds, BITS_PER_LONG); if (max_fds < NR_OPEN_DEFAULT) max_fds = NR_OPEN_DEFAULT; - return min(count, max_fds); + return ALIGN(min(count, max_fds), BITS_PER_LONG); } /*