[PATCH] brcmfmac: Fix a wild pointer dereference bug in brcmf_chip_recognition()

* [PATCH] brcmfmac: Fix a wild pointer dereference bug in brcmf_chip_recognition()
@ 2022-01-24 16:48 Zhou Qingyang
  2022-01-28 10:16 ` Greg KH
  0 siblings, 1 reply; 4+ messages in thread
From: Zhou Qingyang @ 2022-01-24 16:48 UTC (permalink / raw)
  To: zhou1615
  Cc: kjlu, Arend van Spriel, Franky Lin, Hante Meuleman,
	Chi-hsien Lin, Wright Feng, Chung-hsien Hsu, Kalle Valo,
	David S. Miller, Jakub Kicinski, Pieter-Paul Giesberts,
	Angus Ainslie, Daniel (Deognyoun) Kim, John W. Linville,
	linux-wireless, brcm80211-dev-list.pdl, SHA-cyfmac-dev-list,
	netdev, linux-kernel

In brcmf_chip_recognition(), the return value of brcmf_chip_add_core()
is assigned to core and is passed to brcmf_chip_sb_corerev(). In
brcmf_chip_sb_corerev(), there exists dereference of core without check.
the return value of brcmf_chip_add_core() could be ERR_PTR on failure of
allocation, which could lead to a NULL pointer dereference bug.

Fix this bug by adding IS_ERR check for every variable core.

This bug was found by a static analyzer.

Builds with 'make allyesconfig' show no new warnings,
and our static analyzer no longer warns about this code

Fixes: cb7cf7be9eba ("brcmfmac: make chip related functions host interface independent")
Signed-off-by: Zhou Qingyang <zhou1615@umn.edu>
---
The analysis employs differential checking to identify inconsistent 
security operations (e.g., checks or kfrees) between two code paths 
and confirms that the inconsistent operations are not recovered in the
current function or the callers, so they constitute bugs. 

Note that, as a bug found by static analysis, it can be a false
positive or hard to trigger. Multiple researchers have cross-reviewed
the bug.

 .../net/wireless/broadcom/brcm80211/brcmfmac/chip.c    | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/chip.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/chip.c
index 1ee49f9e325d..4d91cb107cd7 100644
--- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/chip.c
+++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/chip.c
@@ -986,18 +986,28 @@ static int brcmf_chip_recognition(struct brcmf_chip_priv *ci)
 
 		core = brcmf_chip_add_core(ci, BCMA_CORE_CHIPCOMMON,
 					   SI_ENUM_BASE_DEFAULT, 0);
+		if (IS_ERR(core))
+			return PTR_ERR(core);
 		brcmf_chip_sb_corerev(ci, core);
 		core = brcmf_chip_add_core(ci, BCMA_CORE_SDIO_DEV,
 					   BCM4329_CORE_BUS_BASE, 0);
+		if (IS_ERR(core))
+			return PTR_ERR(core);
 		brcmf_chip_sb_corerev(ci, core);
 		core = brcmf_chip_add_core(ci, BCMA_CORE_INTERNAL_MEM,
 					   BCM4329_CORE_SOCRAM_BASE, 0);
+		if (IS_ERR(core))
+			return PTR_ERR(core);
 		brcmf_chip_sb_corerev(ci, core);
 		core = brcmf_chip_add_core(ci, BCMA_CORE_ARM_CM3,
 					   BCM4329_CORE_ARM_BASE, 0);
+		if (IS_ERR(core))
+			return PTR_ERR(core);
 		brcmf_chip_sb_corerev(ci, core);
 
 		core = brcmf_chip_add_core(ci, BCMA_CORE_80211, 0x18001000, 0);
+		if (IS_ERR(core))
+			return PTR_ERR(core);
 		brcmf_chip_sb_corerev(ci, core);
 	} else if (socitype == SOCI_AI) {
 		ci->iscoreup = brcmf_chip_ai_iscoreup;
-- 
2.25.1


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