From 90f305f2c7a30257c683e13f4bf7c798eea992a0 Mon Sep 17 00:00:00 2001 From: Dmitry Torokhov Date: Wed, 29 Jul 2026 11:30:45 -0700 Subject: Input: evdev - fix information leak in evdev_pass_values() In evdev_pass_values(), the input_event structure is allocated on the kernel stack and populated field-by-field. However, it is never fully initialized. On architectures where struct input_event contains explicit or implicit padding (such as the 32-bit __pad field on SPARC64), these padding bytes are left uninitialized. When this event structure is subsequently passed to the client buffer and later copied to userspace, the uninitialized padding bytes leak kernel stack memory, potentially exposing sensitive information. Similar issues exist in __evdev_queue_syn_dropped and __pass_event. Fix this by explicitly zeroing the entire event structure with memset() before populating its fields. This ensures all padding bytes are cleared before the data crosses the security boundary. Reported-by: sashiko-bot@kernel.org Cc: stable@vger.kernel.org Link: https://patch.msgid.link/ampGGKo4UMKru6f5@google.com Signed-off-by: Dmitry Torokhov --- drivers/input/evdev.c | 22 ++++++++++++---------- 1 file changed, 12 insertions(+), 10 deletions(-) (limited to 'drivers/input/evdev.c') diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c index c7325226cb86..531db70aa9f9 100644 --- a/drivers/input/evdev.c +++ b/drivers/input/evdev.c @@ -146,11 +146,11 @@ static void __evdev_queue_syn_dropped(struct evdev_client *client) struct timespec64 ts = ktime_to_timespec64(ev_time[client->clk_type]); struct input_event ev; + memset(&ev, 0, sizeof(ev)); ev.input_event_sec = ts.tv_sec; ev.input_event_usec = ts.tv_nsec / NSEC_PER_USEC; ev.type = EV_SYN; ev.code = SYN_DROPPED; - ev.value = 0; client->buffer[client->head++] = ev; client->head &= client->bufsize - 1; @@ -218,20 +218,20 @@ static void __pass_event(struct evdev_client *client, client->head &= client->bufsize - 1; if (unlikely(client->head == client->tail)) { + struct input_event ev; + + memset(&ev, 0, sizeof(ev)); + ev.input_event_sec = event->input_event_sec; + ev.input_event_usec = event->input_event_usec; + ev.type = EV_SYN; + ev.code = SYN_DROPPED; + /* * This effectively "drops" all unconsumed events, leaving * EV_SYN/SYN_DROPPED plus the newest event in the queue. */ client->tail = (client->head - 2) & (client->bufsize - 1); - - client->buffer[client->tail] = (struct input_event) { - .input_event_sec = event->input_event_sec, - .input_event_usec = event->input_event_usec, - .type = EV_SYN, - .code = SYN_DROPPED, - .value = 0, - }; - + client->buffer[client->tail] = ev; client->packet_head = client->tail; } @@ -253,6 +253,8 @@ static void evdev_pass_values(struct evdev_client *client, if (client->revoked) return; + memset(&event, 0, sizeof(event)); + ts = ktime_to_timespec64(ev_time[client->clk_type]); event.input_event_sec = ts.tv_sec; event.input_event_usec = ts.tv_nsec / NSEC_PER_USEC; -- cgit v1.2.3 From 3abd29c61d2ef37c4102cf755b18be53bb9dbea6 Mon Sep 17 00:00:00 2001 From: Dmitry Torokhov Date: Mon, 3 Aug 2026 18:41:49 -0700 Subject: Input: evdev - sanitize event type index when fetching event masks The user-supplied event type index passed to EVIOCGMASK / EVIOCSMASK ioctls is used to index the static counts array in evdev_get_mask_cnt() and client evmasks array in evdev_get_mask(). While the event type is architecturally bounded by EV_CNT, speculative execution may mispredict bounds checks and perform out-of-bounds loads. Sanitize the event type index in evdev_get_mask_cnt() branchlessly using array_index_mask_nospec(). This clamps the index to 0 for safe array access and forces the returned count to 0 speculatively when the index is out of bounds. We do not need additional array_index_nospec() calls in evdev_get_mask() because evdev_get_mask_cnt() speculatively forces the count (and resulting xfer_size) to 0 for out-of-bounds types, preventing any speculative memory access to client evmasks array. Reported-by: "Wagenaar, C.C.J. (Chris)" Cc: stable@vger.kernel.org Assisted-by: Antigravity:gemini-3.6-flash Acked-by: Greg Kroah-Hartman Link: https://patch.msgid.link/anFCAfvxwXB5eJF1@google.com Signed-off-by: Dmitry Torokhov --- drivers/input/evdev.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'drivers/input/evdev.c') diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c index 531db70aa9f9..3a718d600006 100644 --- a/drivers/input/evdev.c +++ b/drivers/input/evdev.c @@ -21,6 +21,7 @@ #include #include #include +#include #include #include #include "input-compat.h" @@ -67,8 +68,10 @@ static size_t evdev_get_mask_cnt(unsigned int type) [EV_SND] = SND_CNT, [EV_FF] = FF_CNT, }; + unsigned long mask = array_index_mask_nospec(type, EV_CNT); - return (type < EV_CNT) ? counts[type] : 0; + /* Returns 0 for out-of-bounds types, including speculatively */ + return counts[type & mask] & mask; } /* requires the buffer lock to be held */ -- cgit v1.2.3