lkml.org 
[lkml]   [2019]   [Dec]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH] fs: jffs2: fix possible sleep-in-atomic-context bugs
Date
The filesystem may sleep while holding a spinlock.
The function call path (from bottom to top) in Linux 4.19 is:

fs/jffs2/malloc.c, 188:
kmem_cache_alloc(GFP_KERNEL) in jffs2_alloc_refblock
fs/jffs2/malloc.c, 221:
jffs2_alloc_refblock in jffs2_prealloc_raw_node_refs
fs/jffs2/wbuf.c, 164:
jffs2_prealloc_raw_node_refs in jffs2_block_refile
fs/jffs2/wbuf.c, 291:
jffs2_block_refile in jffs2_wbuf_recover
fs/jffs2/wbuf.c, 287:
spin_lock in jffs2_wbuf_recover

fs/jffs2/malloc.c, 188:
kmem_cache_alloc(GFP_KERNEL) in jffs2_alloc_refblock
fs/jffs2/malloc.c, 221:
jffs2_alloc_refblock in jffs2_prealloc_raw_node_refs
fs/jffs2/wbuf.c, 164:
jffs2_prealloc_raw_node_refs in jffs2_block_refile
fs/jffs2/wbuf.c, 927:
jffs2_block_refile in jffs2_flash_writev
fs/jffs2/wbuf.c, 924:
spin_lock in jffs2_flash_writev

kmem_cache_alloc(GFP_KERNEL) can sleep at runtime.

To fix these possible bugs, GFP_KERNEL is replaced with GFP_ATOMIC for
kmem_cache_alloc().

These bugs are found by a static analysis tool STCheck written by myself.

Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
---
fs/jffs2/malloc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/jffs2/malloc.c b/fs/jffs2/malloc.c
index ce1189793288..66496ef09716 100644
--- a/fs/jffs2/malloc.c
+++ b/fs/jffs2/malloc.c
@@ -185,7 +185,7 @@ static struct jffs2_raw_node_ref *jffs2_alloc_refblock(void)
{
struct jffs2_raw_node_ref *ret;

- ret = kmem_cache_alloc(raw_node_ref_slab, GFP_KERNEL);
+ ret = kmem_cache_alloc(raw_node_ref_slab, GFP_ATOMIC);
if (ret) {
int i = 0;
for (i=0; i < REFS_PER_BLOCK; i++) {
--
2.17.1
\
 
 \ /
  Last update: 2019-12-17 14:53    [W:0.039 / U:0.684 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site