5.4-stable review patch. If anyone has any objections, please let me know.
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From: Benjamin Tissoires bentiss@kernel.org
commit 4f15ee98304b96e164ff2340e1dfd6181c3f42aa upstream.
When the report ID is not used, the low level transport drivers expect the first byte to be 0. However, currently the allocated buffer not account for that extra byte, meaning that instead of having 8 guaranteed bytes for implement to be working, we only have 7.
Reported-by: Alan Stern stern@rowland.harvard.edu Closes: https://lore.kernel.org/linux-input/c75433e0-9b47-4072-bbe8-b1d14ea97b13@row... Cc: stable@vger.kernel.org Suggested-by: Alan Stern stern@rowland.harvard.edu Link: https://patch.msgid.link/20250710-report-size-null-v2-1-ccf922b7c4e5@kernel.... Signed-off-by: Benjamin Tissoires bentiss@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/hid/hid-core.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
--- a/drivers/hid/hid-core.c +++ b/drivers/hid/hid-core.c @@ -1655,9 +1655,12 @@ u8 *hid_alloc_report_buf(struct hid_repo /* * 7 extra bytes are necessary to achieve proper functionality * of implement() working on 8 byte chunks + * 1 extra byte for the report ID if it is null (not used) so + * we can reserve that extra byte in the first position of the buffer + * when sending it to .raw_request() */
- u32 len = hid_report_len(report) + 7; + u32 len = hid_report_len(report) + 7 + (report->id == 0);
return kzalloc(len, flags); }