[RFC v2 14/43] PKRAM: prevent inadvertent use of a stale superblock
From: Anthony Yznaga <hidden>
Date: 2021-03-30 21:28:29
Also in:
kexec, linux-doc, linux-fsdevel, lkml
Subsystem:
memory management, the rest · Maintainers:
Andrew Morton, Linus Torvalds
When pages have been saved to be preserved by the current boot, set a magic number on the super block to be validated by the next kernel. Signed-off-by: Anthony Yznaga <redacted> --- mm/pkram.c | 9 +++++++++ 1 file changed, 9 insertions(+)
diff --git a/mm/pkram.c b/mm/pkram.c
index dab6657080bf..8670d1633a9d 100644
--- a/mm/pkram.c
+++ b/mm/pkram.c@@ -22,6 +22,7 @@ #include "internal.h" +#define PKRAM_MAGIC 0x706B726D /* * Represents a reference to a data page saved to PKRAM.
@@ -112,6 +113,8 @@ struct pkram_region_list { * The structure occupies a memory page. */ struct pkram_super_block { + __u32 magic; + __u64 node_pfn; /* first element of the node list */ __u64 region_list_pfn; __u64 nr_regions;
@@ -180,6 +183,11 @@ void __init pkram_reserve(void) err = PTR_ERR(pkram_sb); goto out; } + if (pkram_sb->magic != PKRAM_MAGIC) { + pr_err("PKRAM: invalid super block\n"); + err = -EINVAL; + goto out; + } /* An empty pkram_sb is not an error */ if (!pkram_sb->node_pfn) { pkram_sb = NULL;
@@ -993,6 +1001,7 @@ static void __pkram_reboot(void) */ memset(pkram_sb, 0, PAGE_SIZE); if (!err && node_pfn) { + pkram_sb->magic = PKRAM_MAGIC; pkram_sb->node_pfn = node_pfn; pkram_sb->region_list_pfn = rl_pfn; pkram_sb->nr_regions = nr_regions;
--
1.8.3.1