From c94751025737d3a0096fe4a78a02b17581dfdde6 Mon Sep 17 00:00:00 2001 From: Rasmus Villemoes Date: Fri, 28 Jun 2013 09:52:24 +1000 Subject: [PATCH] mm: mremap: validate input before taking lock This patch is very similar to 84d96d897671 ("mm: madvise: complete input validation before taking lock"): perform some basic validation of the input to mremap() before taking the ¤t->mm->mmap_sem lock. This also makes the MREMAP_FIXED => MREMAP_MAYMOVE dependency slightly more explicit. Signed-off-by: Rasmus Villemoes Cc: KOSAKI Motohiro Cc: David Rientjes Signed-off-by: Andrew Morton --- mm/mremap.c | 18 ++++++++++-------- 1 file changed, 10 insertions(+), 8 deletions(-) diff --git a/mm/mremap.c b/mm/mremap.c index 3708655378e9..457d34ef3bf2 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -456,13 +456,14 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len, unsigned long charged = 0; bool locked = false; - down_write(¤t->mm->mmap_sem); - if (flags & ~(MREMAP_FIXED | MREMAP_MAYMOVE)) - goto out; + return ret; + + if (flags & MREMAP_FIXED && !(flags & MREMAP_MAYMOVE)) + return ret; if (addr & ~PAGE_MASK) - goto out; + return ret; old_len = PAGE_ALIGN(old_len); new_len = PAGE_ALIGN(new_len); @@ -473,12 +474,13 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len, * a zero new-len is nonsensical. */ if (!new_len) - goto out; + return ret; + + down_write(¤t->mm->mmap_sem); if (flags & MREMAP_FIXED) { - if (flags & MREMAP_MAYMOVE) - ret = mremap_to(addr, old_len, new_addr, new_len, - &locked); + ret = mremap_to(addr, old_len, new_addr, new_len, + &locked); goto out; } -- 2.39.5