7.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Niklas Schnelle commit 8ac60ae2a307a50b599bf5d300b448d638f3ba29 upstream. While report_error_write() checks that the provided buffer is at least as large as the header struct, but not that it is large enough to contain the report with the length claimed by report->length. If user-space provides a short buffer, meaning a larger report->length than the actually written payload, up to around 4K of kernel data from past the kmalloc(len + 1) sized buffer allocated in kernfs_fop_write_iter() will leak into the SCLP report. However, as the entity processing the SCLP is privileged and able to access at least the page including the report, this does not leak data that entity could not access but it is still an out of bounds read and a malformed error report that should be rejected. Fixes: 368704a65be8 ("s390/pci: add report_error attribute") Cc: stable@vger.kernel.org Signed-off-by: Niklas Schnelle Reviewed-by: Benjamin Block Signed-off-by: Vasily Gorbik Signed-off-by: Heiko Carstens Signed-off-by: Greg Kroah-Hartman --- arch/s390/pci/pci_sysfs.c | 3 +++ 1 file changed, 3 insertions(+) --- a/arch/s390/pci/pci_sysfs.c +++ b/arch/s390/pci/pci_sysfs.c @@ -153,6 +153,9 @@ static ssize_t report_error_write(struct if (off || (count < sizeof(*report))) return -EINVAL; + if (count < (report->length + sizeof(*report))) + return -EINVAL; + ret = sclp_pci_report(report, zdev->fh, zdev->fid); return ret ? ret : count;