From e873c74132f0c5f1452816cd9bb26208f0bba1e1 Mon Sep 17 00:00:00 2001 From: Shivank Garg Date: Sat, 22 Aug 2026 19:22:05 +0000 Subject: dmaengine: fix use-after-free in dma_chan_put() and dma_release_channel() When dma_device_put() drops the last reference on chan->device->ref, dma_device_release() runs and may free the dma_device along with its channels. dma_chan_put() then still reads chan->device->owner via dma_chan_to_owner() for the trailing module_put(). KASAN catches it: slab-use-after-free in dma_chan_put+0x3e6/0x4c0 Read of size 8 by task insmod/6319 Freed by task 6319: kfree+0x225/0x470 dma_chan_put+0x395/0x4c0 dmaengine_put+0xf8/0x160 Cache the module owner in dma_chan_put() before the put so the trailing module_put() does not need chan->device. Fixes: 8ad342a86359 ("dmaengine: Add reference counting to dma_device struct") Suggested-by: Sashiko Link: https://sashiko.dev/#/patchset/20260518-dmaengine-kref-fix-v1-1-4d6125048fb7@amd.com Reviewed-by: Frank Li Reviewed-by: Logan Gunthorpe Signed-off-by: Shivank Garg Link: https://patch.msgid.link/20260822-dmaengine-kref-fix-v5-3-d4a4ee47d927@amd.com Signed-off-by: Vinod Koul --- scripts/coccinelle/null/badzero.cocci | 239 ++++++++++++++++++++++++++++++++++ 1 file changed, 239 insertions(+) create mode 100644 scripts/coccinelle/null/badzero.cocci (limited to 'scripts/coccinelle/null/badzero.cocci') diff --git a/scripts/coccinelle/null/badzero.cocci b/scripts/coccinelle/null/badzero.cocci new file mode 100644 index 000000000..35d443825 --- /dev/null +++ b/scripts/coccinelle/null/badzero.cocci @@ -0,0 +1,239 @@ +// SPDX-License-Identifier: GPL-2.0-only +/// Compare pointer-typed values to NULL rather than 0 +/// +//# This makes an effort to choose between !x and x == NULL. !x is used +//# if it has previously been used with the function used to initialize x. +//# This relies on type information. More type information can be obtained +//# using the option -all_includes and the option -I to specify an +//# include path. +// +// Confidence: High +// Copyright: (C) 2012 Julia Lawall, INRIA/LIP6. +// Copyright: (C) 2012 Gilles Muller, INRIA/LiP6. +// URL: https://coccinelle.gitlabpages.inria.fr/website +// Requires: 1.0.0 +// Options: + +virtual patch +virtual context +virtual org +virtual report + +@initialize:ocaml@ +@@ +let negtable = Hashtbl.create 101 + +@depends on patch@ +expression *E; +identifier f; +@@ + +( + (E = f(...)) == +- 0 ++ NULL +| + (E = f(...)) != +- 0 ++ NULL +| +- 0 ++ NULL + == (E = f(...)) +| +- 0 ++ NULL + != (E = f(...)) +) + + +@t1 depends on !patch@ +expression *E; +identifier f; +position p; +@@ + +( + (E = f(...)) == +* 0@p +| + (E = f(...)) != +* 0@p +| +* 0@p + == (E = f(...)) +| +* 0@p + != (E = f(...)) +) + +@script:python depends on org@ +p << t1.p; +@@ + +coccilib.org.print_todo(p[0], "WARNING comparing pointer to 0") + +@script:python depends on report@ +p << t1.p; +@@ + +coccilib.report.print_report(p[0], "WARNING comparing pointer to 0") + +// Tests of returned values + +@s@ +identifier f; +expression E,E1; +@@ + + E = f(...) + ... when != E = E1 + !E + +@script:ocaml depends on s@ +f << s.f; +@@ + +try let _ = Hashtbl.find negtable f in () +with Not_found -> Hashtbl.add negtable f () + +@ r disable is_zero,isnt_zero exists @ +expression *E; +identifier f; +@@ + +E = f(...) +... +(E == 0 +|E != 0 +|0 == E +|0 != E +) + +@script:ocaml@ +f << r.f; +@@ + +try let _ = Hashtbl.find negtable f in () +with Not_found -> include_match false + +// This rule may lead to inconsistent path problems, if E is defined in two +// places +@ depends on patch disable is_zero,isnt_zero @ +expression *E; +expression E1; +identifier r.f; +@@ + +E = f(...) +<... +( +- E == 0 ++ !E +| +- E != 0 ++ E +| +- 0 == E ++ !E +| +- 0 != E ++ E +) +...> +?E = E1 + +@t2 depends on !patch disable is_zero,isnt_zero @ +expression *E; +expression E1; +identifier r.f; +position p1; +position p2; +@@ + +E = f(...) +<... +( +* E == 0@p1 +| +* E != 0@p2 +| +* 0@p1 == E +| +* 0@p1 != E +) +...> +?E = E1 + +@script:python depends on org@ +p << t2.p1; +@@ + +coccilib.org.print_todo(p[0], "WARNING comparing pointer to 0, suggest !E") + +@script:python depends on org@ +p << t2.p2; +@@ + +coccilib.org.print_todo(p[0], "WARNING comparing pointer to 0") + +@script:python depends on report@ +p << t2.p1; +@@ + +coccilib.report.print_report(p[0], "WARNING comparing pointer to 0, suggest !E") + +@script:python depends on report@ +p << t2.p2; +@@ + +coccilib.report.print_report(p[0], "WARNING comparing pointer to 0") + +@ depends on patch disable is_zero,isnt_zero @ +expression *E; +@@ + +( + E == +- 0 ++ NULL +| + E != +- 0 ++ NULL +| +- 0 ++ NULL + == E +| +- 0 ++ NULL + != E +) + +@ t3 depends on !patch disable is_zero,isnt_zero @ +expression *E; +position p; +@@ + +( +* E == 0@p +| +* E != 0@p +| +* 0@p == E +| +* 0@p != E +) + +@script:python depends on org@ +p << t3.p; +@@ + +coccilib.org.print_todo(p[0], "WARNING comparing pointer to 0") + +@script:python depends on report@ +p << t3.p; +@@ + +coccilib.report.print_report(p[0], "WARNING comparing pointer to 0") -- cgit v1.3.1