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Subject[PATCH 1/3] pstore: pass allocated memory region back to caller
Date
The buf_lock cannot be held while populating the inodes, so make the backend
pass forward an allocated and filled buffer instead. Solves this backtrace:

[ 59.691019] BUG: sleeping function called from invalid context at .../mm/slub.c:847
[ 59.691019] in_atomic(): 0, irqs_disabled(): 1, pid: 1819, name: mount
[ 59.691019] Pid: 1819, comm: mount Not tainted 3.0.8 #1
[ 59.691019] Call Trace:
[ 59.691019] [<810252d5>] __might_sleep+0xc3/0xca
[ 59.691019] [<810a26e6>] kmem_cache_alloc+0x32/0xf3
[ 59.691019] [<810b53ac>] ? __d_lookup_rcu+0x6f/0xf4
[ 59.691019] [<810b68b1>] alloc_inode+0x2a/0x64
[ 59.691019] [<810b6903>] new_inode+0x18/0x43
[ 59.691019] [<81142447>] pstore_get_inode.isra.1+0x11/0x98
[ 59.691019] [<81142623>] pstore_mkfile+0xae/0x26f
[ 59.691019] [<810a2a66>] ? kmem_cache_free+0x19/0xb1
[ 59.691019] [<8116c821>] ? ida_get_new_above+0x140/0x158
[ 59.691019] [<811708ea>] ? __init_rwsem+0x1e/0x2c
[ 59.691019] [<810b67e8>] ? inode_init_always+0x111/0x1b0
[ 59.691019] [<8102127e>] ? should_resched+0xd/0x27
[ 59.691019] [<8137977f>] ? _cond_resched+0xd/0x21
[ 59.691019] [<81142abf>] pstore_get_records+0x52/0xa7
[ 59.691019] [<8114254b>] pstore_fill_super+0x7d/0x91
[ 59.691019] [<810a7ff5>] mount_single+0x46/0x82
[ 59.691019] [<8114231a>] pstore_mount+0x15/0x17
[ 59.691019] [<811424ce>] ? pstore_get_inode.isra.1+0x98/0x98
[ 59.691019] [<810a8199>] mount_fs+0x5a/0x12d
[ 59.691019] [<810b9174>] ? alloc_vfsmnt+0xa4/0x14a
[ 59.691019] [<810b9474>] vfs_kern_mount+0x4f/0x7d
[ 59.691019] [<810b9d7e>] do_kern_mount+0x34/0xb2
[ 59.691019] [<810bb15f>] do_mount+0x5fc/0x64a
[ 59.691019] [<810912fb>] ? strndup_user+0x2e/0x3f
[ 59.691019] [<810bb3cb>] sys_mount+0x66/0x99
[ 59.691019] [<8137b537>] sysenter_do_call+0x12/0x26

Signed-off-by: Kees Cook <keescook@chromium.org>
---
fs/pstore/platform.c | 14 +++++++-------
include/linux/pstore.h | 3 ++-
2 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index 2bd620f..c09cbb4 100644
--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -195,30 +195,30 @@ EXPORT_SYMBOL_GPL(pstore_register);
void pstore_get_records(int quiet)
{
struct pstore_info *psi = psinfo;
+ char *buf = NULL;
ssize_t size;
u64 id;
enum pstore_type_id type;
struct timespec time;
int failed = 0, rc;
- unsigned long flags;

if (!psi)
return;

- spin_lock_irqsave(&psinfo->buf_lock, flags);
rc = psi->open(psi);
if (rc)
goto out;

- while ((size = psi->read(&id, &type, &time, psi)) > 0) {
- rc = pstore_mkfile(type, psi->name, id, psi->buf, (size_t)size,
+ while ((size = psi->read(&id, &type, &time, &buf, psi)) > 0) {
+ rc = pstore_mkfile(type, psi->name, id, buf, (size_t)size,
time, psi);
+ kfree(buf);
+ buf = NULL;
if (rc && (rc != -EEXIST || !quiet))
failed++;
}
psi->close(psi);
out:
- spin_unlock_irqrestore(&psinfo->buf_lock, flags);

if (failed)
printk(KERN_WARNING "pstore: failed to load %d record(s) from '%s'\n",
@@ -259,10 +259,10 @@ int pstore_write(enum pstore_type_id type, char *buf, size_t size)
spin_lock_irqsave(&psinfo->buf_lock, flags);
memcpy(psinfo->buf, buf, size);
ret = psinfo->write(type, &id, 0, size, psinfo);
+ spin_unlock_irqrestore(&psinfo->buf_lock, flags);
if (ret == 0 && pstore_is_mounted())
- pstore_mkfile(PSTORE_TYPE_DMESG, psinfo->name, id, psinfo->buf,
+ pstore_mkfile(PSTORE_TYPE_DMESG, psinfo->name, id, buf,
size, CURRENT_TIME, psinfo);
- spin_unlock_irqrestore(&psinfo->buf_lock, flags);

return 0;
}
diff --git a/include/linux/pstore.h b/include/linux/pstore.h
index ea56732..781cf43 100644
--- a/include/linux/pstore.h
+++ b/include/linux/pstore.h
@@ -38,7 +38,8 @@ struct pstore_info {
int (*open)(struct pstore_info *psi);
int (*close)(struct pstore_info *psi);
ssize_t (*read)(u64 *id, enum pstore_type_id *type,
- struct timespec *time, struct pstore_info *psi);
+ struct timespec *time, char **buf,
+ struct pstore_info *psi);
int (*write)(enum pstore_type_id type, u64 *id,
unsigned int part, size_t size, struct pstore_info *psi);
int (*erase)(enum pstore_type_id type, u64 id,
--
1.7.0.4


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