From: Takashi Iwai tiwai@suse.de
This patch has been added to the 4.1 stable tree. If you have any objections, please let us know.
===============
[ Upstream commit bb82e0b4a7e96494f0c1004ce50cec3d7b5fb3d1 ]
The commit f6f828513290 ("pstore: pass allocated memory region back to caller") changed the check of the return value from erst_read() in erst_reader() in the following way:
if (len == -ENOENT) goto skip; - else if (len < 0) { - rc = -1; + else if (len < sizeof(*rcd)) { + rc = -EIO; goto out;
This introduced another bug: since the comparison with sizeof() is cast to unsigned, a negative len value doesn't hit any longer. As a result, when an error is returned from erst_read(), the code falls through, and it may eventually lead to some weird thing like memory corruption.
This patch adds the negative error value check more explicitly for addressing the issue.
Fixes: f6f828513290 (pstore: pass allocated memory region back to caller) Cc: All applicable stable@vger.kernel.org Tested-by: Jerry Tang jtang@suse.com Signed-off-by: Takashi Iwai tiwai@suse.de Acked-by: Kees Cook keescook@chromium.org Reviewed-by: Borislav Petkov bp@suse.de Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com --- drivers/acpi/apei/erst.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/acpi/apei/erst.c b/drivers/acpi/apei/erst.c index ed65e9c4b5b0..ba4930c0e98c 100644 --- a/drivers/acpi/apei/erst.c +++ b/drivers/acpi/apei/erst.c @@ -1023,7 +1023,7 @@ static ssize_t erst_reader(u64 *id, enum pstore_type_id *type, int *count, /* The record may be cleared by others, try read next record */ if (len == -ENOENT) goto skip; - else if (len < sizeof(*rcd)) { + else if (len < 0 || len < sizeof(*rcd)) { rc = -EIO; goto out; }