From 50c6dbdfd16e312382842198a7919341ad480e05 Mon Sep 17 00:00:00 2001 From: Max Ramanouski Date: Sun, 25 Aug 2024 01:01:11 +0300 Subject: [PATCH] x86/ioremap: Improve iounmap() address range checks Allowing iounmap() on memory that was not ioremap()'d in the first place is obviously a bad idea. There is currently a feeble attempt to avoid errant iounmap()s by checking to see if the address is below "high_memory". But that's imprecise at best because there are plenty of high addresses that are also invalid to call iounmap() on. Thankfully, there is a more precise helper: is_ioremap_addr(). x86 just does not use it in iounmap(). Restrict iounmap() to addresses in the ioremap region, by using is_ioremap_addr(). This aligns x86 closer to the generic iounmap() implementation. Additionally, add a warning in case there is an attempt to iounmap() invalid memory. This replaces an existing silent return and will help alert folks to any incorrect usage of iounmap(). Due to VMALLOC_START on i386 not being present in asm/pgtable.h, include for asm/vmalloc.h had to be added to include/linux/ioremap.h. [ dhansen: tweak subject and changelog ] Signed-off-by: Max Ramanouski Signed-off-by: Dave Hansen Reviewed-by: Christoph Hellwig Reviewed-by: Alistair Popple Link: https://lore.kernel.org/all/20240824220111.84441-1-max8rr8%40gmail.com --- arch/x86/mm/ioremap.c | 3 ++- include/linux/ioremap.h | 1 + 2 files changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c index aa7d279321ea..70b02fc61d93 100644 --- a/arch/x86/mm/ioremap.c +++ b/arch/x86/mm/ioremap.c @@ -11,6 +11,7 @@ #include #include #include +#include #include #include #include @@ -457,7 +458,7 @@ void iounmap(volatile void __iomem *addr) { struct vm_struct *p, *o; - if ((void __force *)addr <= high_memory) + if (WARN_ON_ONCE(!is_ioremap_addr((void __force *)addr))) return; /* diff --git a/include/linux/ioremap.h b/include/linux/ioremap.h index f0e99fc7dd8b..2bd1661fe9ad 100644 --- a/include/linux/ioremap.h +++ b/include/linux/ioremap.h @@ -4,6 +4,7 @@ #include #include +#include #if defined(CONFIG_HAS_IOMEM) || defined(CONFIG_GENERIC_IOREMAP) /* -- 2.42.0