From 0e4d7df2f3b2e59c1bccc09ea099b7a6c2dda886 Mon Sep 17 00:00:00 2001 From: "Russell King (Oracle)" Date: Wed, 28 Jan 2026 10:51:56 +0000 Subject: [PATCH] net: phylink: fix NULL pointer deref in phylink_major_config() When a MAC driver returns a PCS for an interface mode, and then we attempt to switch to a different mode that doesn't require a PCS, this causes phylink to oops: Unable to handle kernel NULL pointer dereference at virtual address 0000000000000010 Mem abort info: ESR = 0x0000000096000044 EC = 0x25: DABT (current EL), IL = 32 bits SET = 0, FnV = 0 EA = 0, S1PTW = 0 FSC = 0x04: level 0 translation fault Data abort info: ISV = 0, ISS = 0x00000044, ISS2 = 0x00000000 CM = 0, WnR = 1, TnD = 0, TagAccess = 0 GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0 user pgtable: 4k pages, 48-bit VAs, pgdp=0000000137f96000 [0000000000000010] pgd=0000000000000000, p4d=0000000000000000 Internal error: Oops: 0000000096000044 [#1] SMP Modules linked in: -- CPU: 1 UID: 0 PID: 55 Comm: kworker/u33:0 Not tainted 6.19.0-rc5-00581-g73cb8467a63e #1 PREEMPT Hardware name: Qualcomm Technologies, Inc. Lemans Ride Rev3 (DT) Workqueue: events_power_efficient phylink_resolve pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS +BTYPE=--) pc : phylink_major_config+0x408/0x948 lr : phylink_major_config+0x3fc/0x948 sp : ffff800080353c60 x29: ffff800080353cb0 x28: ffffb305068a8a00 x27: ffffb305068a8000 x26: ffff000080092100 x25: 0000000000000000 x24: 0000000000000000 x23: 0000000000000001 x22: 0000000000000000 x21: ffffb3050555b3d0 x20: ffff800080353d10 x19: ffff0000b6059400 x18: 00000000ffffffff x17: 74756f2f79687020 x16: ffffb305045e4f18 x15: 6769666e6f632072 x14: 6f6a616d203a3168 x13: 782d657361623030 x12: ffffb305068c6a98 x11: 0000000000000583 x10: 0000000000000018 x9 : ffffb305068c6a98 x8 : 0000000100006583 x7 : 0000000000000000 x6 : ffff00008083cc40 x5 : ffff00008083cc40 x4 : 0000000000000001 x3 : 0000000000000001 x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff0000b269e5a8 Call trace: phylink_major_config+0x408/0x948 (P) phylink_resolve+0x294/0x6e4 process_one_work+0x148/0x28c worker_thread+0x2d8/0x3d8 kthread+0x134/0x208 ret_from_fork+0x10/0x20 Code: d63f0020 f9400e60 b4000040 f900081f (f9000ad3) ---[ end trace 0000000000000000 ]--- This is caused by "pcs" being NULL when we attempt to execute: pcs->phylink = pl; Make this conditional on pcs being non-null. Fixes: 486dc391ef43 ("net: phylink: allow mac_select_pcs() to remove a PCS") Reported-by: Mohd Ayaan Anwar Signed-off-by: Russell King (Oracle) Link: https://patch.msgid.link/E1vl39Q-00000006utm-229h@rmk-PC.armlinux.org.uk Signed-off-by: Jakub Kicinski --- drivers/net/phy/phylink.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c index 7641f1f41e39..e1f01d7fc4da 100644 --- a/drivers/net/phy/phylink.c +++ b/drivers/net/phy/phylink.c @@ -1293,7 +1293,8 @@ static void phylink_major_config(struct phylink *pl, bool restart, if (pl->pcs) pl->pcs->phylink = NULL; - pcs->phylink = pl; + if (pcs) + pcs->phylink = pl; pl->pcs = pcs; } -- 2.47.3