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media: vidtv: fix NULL pointer dereference in vidtv_mux_push_si

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commit 7d8bf3d8f9 upstream.

syzbot reported a general protection fault in
vidtv_psi_ts_psi_write_into [1].

vidtv_mux_get_pid_ctx() can return NULL, but vidtv_mux_push_si() does
not check for this before dereferencing the returned pointer to access
the continuity counter. This leads to a general protection fault when
accessing a near-NULL address.

The root cause is that vidtv_mux_pid_ctx_init() does not check the
return value of vidtv_mux_create_pid_ctx_once() for PMT section PIDs.
If the allocation fails, the PID context is never created, but init
returns success. The subsequent vidtv_mux_push_si() call then gets
NULL from vidtv_mux_get_pid_ctx() and crashes.

Fix both the root cause (add error check in vidtv_mux_pid_ctx_init
for PMT PIDs) and add defensive NULL checks in vidtv_mux_push_si for
all vidtv_mux_get_pid_ctx() calls.

[1]
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
Workqueue: events vidtv_mux_tick
RIP: 0010:vidtv_psi_ts_psi_write_into+0x54a/0xbc0 drivers/media/test-drivers/vidtv/vidtv_psi.c:197
Call Trace:
 <TASK>
 vidtv_psi_table_header_write_into drivers/media/test-drivers/vidtv/vidtv_psi.c:799 [inline]
 vidtv_psi_pmt_write_into+0x3b2/0xa70 drivers/media/test-drivers/vidtv/vidtv_psi.c:1231
 vidtv_mux_push_si+0x932/0xe80 drivers/media/test-drivers/vidtv/vidtv_mux.c:196
 vidtv_mux_tick+0xe9b/0x1480 drivers/media/test-drivers/vidtv/vidtv_mux.c:408

Fixes: f90cf6079b ("media: vidtv: add a bridge driver")
Cc: stable@vger.kernel.org
Reported-by: syzbot+814c351d094f4f1a1b86@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=814c351d094f4f1a1b86
Signed-off-by: Ruslan Valiyev <linuxoid@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ruslan Valiyev
2026-03-17 17:05:44 +00:00
committed by Greg Kroah-Hartman
parent 43a6281790
commit 455bc12e7b
1 changed files with 7 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files
drivers/media/test-drivers/vidtv/vidtv_mux.c
+7 -1
View File
@@ -101,7 +101,8 @@ static int vidtv_mux_pid_ctx_init(struct vidtv_mux *m)
/* add a ctx for all PMT sections */
while (p) {
pid = vidtv_psi_get_pat_program_pid(p);
vidtv_mux_create_pid_ctx_once(m, pid);
if (!vidtv_mux_create_pid_ctx_once(m, pid))
goto free;
p = p->next;
}
@@ -170,6 +171,9 @@ static u32 vidtv_mux_push_si(struct vidtv_mux *m)
nit_ctx = vidtv_mux_get_pid_ctx(m, VIDTV_NIT_PID);
eit_ctx = vidtv_mux_get_pid_ctx(m, VIDTV_EIT_PID);
if (!pat_ctx || !sdt_ctx || !nit_ctx || !eit_ctx)
return 0;
pat_args.offset = m->mux_buf_offset;
pat_args.continuity_counter = &pat_ctx->cc;
@@ -186,6 +190,8 @@ static u32 vidtv_mux_push_si(struct vidtv_mux *m)
}
pmt_ctx = vidtv_mux_get_pid_ctx(m, pmt_pid);
if (!pmt_ctx)
continue;
pmt_args.offset = m->mux_buf_offset;
pmt_args.pmt = m->si.pmt_secs[i];