linux-kernel - [PATCH] pstore: fix incorrect persistent ram buffer mapping

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Date:   Wed, 12 Sep 2018 03:36:34 +0000
From:   Bin Yang <bin.yang@...el.com>
To:     keescook@...omium.org, anton@...msg.org, ccross@...roid.com,
        tony.luck@...el.com, linux-kernel@...r.kernel.org,
        bin.yang@...el.com
Subject: [PATCH] pstore: fix incorrect persistent ram buffer mapping

persistent_ram_vmap() returns the page start vaddr.
persistent_ram_iomap() supports non-page-aligned mapping.

persistent_ram_buffer_map() always adds offset-in-page to the vaddr
returned from these two functions, which causes incorrect mapping of
non-page-aligned persistent ram buffer.

Signed-off-by: Bin Yang <bin.yang@...el.com>
---
 fs/pstore/ram_core.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/pstore/ram_core.c b/fs/pstore/ram_core.c
index 951a14e..7c05fdd 100644
--- a/fs/pstore/ram_core.c
+++ b/fs/pstore/ram_core.c
@@ -429,7 +429,7 @@ static void *persistent_ram_vmap(phys_addr_t start, size_t size,
 	vaddr = vmap(pages, page_count, VM_MAP, prot);
 	kfree(pages);
 
-	return vaddr;
+	return vaddr + offset_in_page(start);
 }
 
 static void *persistent_ram_iomap(phys_addr_t start, size_t size,
@@ -468,7 +468,7 @@ static int persistent_ram_buffer_map(phys_addr_t start, phys_addr_t size,
 		return -ENOMEM;
 	}
 
-	prz->buffer = prz->vaddr + offset_in_page(start);
+	prz->buffer = prz->vaddr;
 	prz->buffer_size = size - sizeof(struct persistent_ram_buffer);
 
 	return 0;
@@ -515,7 +515,7 @@ void persistent_ram_free(struct persistent_ram_zone *prz)
 
 	if (prz->vaddr) {
 		if (pfn_valid(prz->paddr >> PAGE_SHIFT)) {
-			vunmap(prz->vaddr);
+			vunmap(prz->vaddr - offset_in_page(prz->paddr));
 		} else {
 			iounmap(prz->vaddr);
 			release_mem_region(prz->paddr, prz->size);
-- 
2.7.4