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Subject[PATCH 2/3] erst: pass back allocated buffer for pstore
Date
Since pstore cannot hold the buf_lock while it populates the VFS, the backend
needs to do it instead, and provide an allocated buffer with the contents.

Signed-off-by: Kees Cook <keescook@chromium.org>
---
drivers/acpi/apei/erst.c | 21 ++++++++++++++++-----
1 files changed, 16 insertions(+), 5 deletions(-)

diff --git a/drivers/acpi/apei/erst.c b/drivers/acpi/apei/erst.c
index 1274080..b8b97d6 100644
--- a/drivers/acpi/apei/erst.c
+++ b/drivers/acpi/apei/erst.c
@@ -932,7 +932,8 @@ static int erst_check_table(struct acpi_table_erst *erst_tab)
static int erst_open_pstore(struct pstore_info *psi);
static int erst_close_pstore(struct pstore_info *psi);
static ssize_t erst_reader(u64 *id, enum pstore_type_id *type,
- struct timespec *time, struct pstore_info *psi);
+ struct timespec *time, char **buf,
+ struct pstore_info *psi);
static int erst_writer(enum pstore_type_id type, u64 *id, unsigned int part,
size_t size, struct pstore_info *psi);
static int erst_clearer(enum pstore_type_id type, u64 id,
@@ -986,17 +987,20 @@ static int erst_close_pstore(struct pstore_info *psi)
}

static ssize_t erst_reader(u64 *id, enum pstore_type_id *type,
- struct timespec *time, struct pstore_info *psi)
+ struct timespec *time, char **buf,
+ struct pstore_info *psi)
{
int rc;
ssize_t len = 0;
u64 record_id;
struct cper_pstore_record *rcd = (struct cper_pstore_record *)
(erst_info.buf - sizeof(*rcd));
+ unsigned long flags;

if (erst_disable)
return -ENODEV;

+ spin_lock_irqsave(&erst_info.buf_lock, flags);
skip:
rc = erst_get_record_id_next(&reader_pos, &record_id);
if (rc)
@@ -1004,7 +1008,7 @@ skip:

/* no more record */
if (record_id == APEI_ERST_INVALID_RECORD_ID) {
- rc = -1;
+ rc = -EINVAL;
goto out;
}

@@ -1013,13 +1017,19 @@ skip:
/* The record may be cleared by others, try read next record */
if (len == -ENOENT)
goto skip;
- else if (len < 0) {
- rc = -1;
+ else if (len < sizeof(*rcd)) {
+ rc = -EIO;
goto out;
}
if (uuid_le_cmp(rcd->hdr.creator_id, CPER_CREATOR_PSTORE) != 0)
goto skip;

+ *buf = kmalloc(len, GFP_KERNEL);
+ if (*buf == NULL) {
+ rc = -ENOMEM;
+ goto out;
+ }
+ memcpy(*buf, erst_info.buf, len - sizeof(*rcd));
*id = record_id;
if (uuid_le_cmp(rcd->sec_hdr.section_type,
CPER_SECTION_TYPE_DMESG) == 0)
@@ -1037,6 +1047,7 @@ skip:
time->tv_nsec = 0;

out:
+ spin_unlock_irqrestore(&erst_info.buf_lock, flags);
return (rc < 0) ? rc : (len - sizeof(*rcd));
}

--
1.7.0.4


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