From 43e11fa2d1d3b6e35629fa556eb7d571edba2010 Mon Sep 17 00:00:00 2001 From: "Gustavo A. R. Silva" Date: Tue, 16 Jul 2019 16:30:58 -0700 Subject: [PATCH] fs/select.c: use struct_size() in kmalloc() One of the more common cases of allocation size calculations is finding the size of a structure that has a zero-sized array at the end, along with memory for some number of elements for that array. For example: struct foo { int stuff; struct boo entry[]; }; size = sizeof(struct foo) + count * sizeof(struct boo); instance = kmalloc(size, GFP_KERNEL); Instead of leaving these open-coded and prone to type mistakes, we can now use the new struct_size() helper: instance = kmalloc(struct_size(instance, entry, count), GFP_KERNEL); Also, notice that variable size is unnecessary, hence it is removed. This code was detected with the help of Coccinelle. Link: http://lkml.kernel.org/r/20190604164226.GA13823@embeddedor Signed-off-by: Gustavo A. R. Silva Reviewed-by: Andrew Morton Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/select.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/fs/select.c b/fs/select.c index 51ceec292f2f..53a0c149f528 100644 --- a/fs/select.c +++ b/fs/select.c @@ -961,7 +961,7 @@ static int do_sys_poll(struct pollfd __user *ufds, unsigned int nfds, struct timespec64 *end_time) { struct poll_wqueues table; - int err = -EFAULT, fdcount, len, size; + int err = -EFAULT, fdcount, len; /* Allocate small arguments on the stack to save memory and be faster - use long to make sure the buffer is aligned properly on 64 bit archs to avoid unaligned access */ @@ -989,8 +989,8 @@ static int do_sys_poll(struct pollfd __user *ufds, unsigned int nfds, break; len = min(todo, POLLFD_PER_PAGE); - size = sizeof(struct poll_list) + sizeof(struct pollfd) * len; - walk = walk->next = kmalloc(size, GFP_KERNEL); + walk = walk->next = kmalloc(struct_size(walk, entries, len), + GFP_KERNEL); if (!walk) { err = -ENOMEM; goto out_fds;