From b359ed5184aebf9d987e54abc5dae7ac03ed29ae Mon Sep 17 00:00:00 2001 From: Jean-Philippe Brucker Date: Fri, 17 Apr 2020 16:23:26 +0200 Subject: [PATCH 1/2] mtd: cfi_cmdset_0001: Support the absence of protection registers MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The flash controller implemented by the Arm Base platform behaves like the Intel StrataFlash J3 device, but omits several features. In particular it doesn't implement a protection register, so "Number of Protection register fields" in the Primary Vendor-Specific Extended Query, is 0. The Intel StrataFlash J3 datasheet only lists 1 as a valid value for NumProtectionFields. It describes the field as: "Number of Protection register fields in JEDEC ID space. “00h,” indicates that 256 protection bytes are available" While a value of 0 may arguably not be architecturally valid, the driver's current behavior is certainly wrong: if NumProtectionFields is 0, read_pri_intelext() adds a negative value to the unsigned extra_size, and ends up in an infinite loop. Fix it by ignoring a NumProtectionFields of 0. Signed-off-by: Jean-Philippe Brucker Tested-by: Sudeep Holla Tested-by: Catalin Marinas Signed-off-by: Vignesh Raghavendra --- drivers/mtd/chips/cfi_cmdset_0001.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/drivers/mtd/chips/cfi_cmdset_0001.c b/drivers/mtd/chips/cfi_cmdset_0001.c index 142c0f9485fe..42001c49833b 100644 --- a/drivers/mtd/chips/cfi_cmdset_0001.c +++ b/drivers/mtd/chips/cfi_cmdset_0001.c @@ -420,8 +420,9 @@ read_pri_intelext(struct map_info *map, __u16 adr) extra_size = 0; /* Protection Register info */ - extra_size += (extp->NumProtectionFields - 1) * - sizeof(struct cfi_intelext_otpinfo); + if (extp->NumProtectionFields) + extra_size += (extp->NumProtectionFields - 1) * + sizeof(struct cfi_intelext_otpinfo); } if (extp->MinorVersion >= '1') { @@ -695,14 +696,16 @@ static int cfi_intelext_partition_fixup(struct mtd_info *mtd, */ if (extp && extp->MajorVersion == '1' && extp->MinorVersion >= '3' && extp->FeatureSupport & (1 << 9)) { + int offs = 0; struct cfi_private *newcfi; struct flchip *chip; struct flchip_shared *shared; - int offs, numregions, numparts, partshift, numvirtchips, i, j; + int numregions, numparts, partshift, numvirtchips, i, j; /* Protection Register info */ - offs = (extp->NumProtectionFields - 1) * - sizeof(struct cfi_intelext_otpinfo); + if (extp->NumProtectionFields) + offs = (extp->NumProtectionFields - 1) * + sizeof(struct cfi_intelext_otpinfo); /* Burst Read info */ offs += extp->extra[offs+1]+2; From 11399346ac39a26ade2a90303d38ad318163c665 Mon Sep 17 00:00:00 2001 From: "Gustavo A. R. Silva" Date: Thu, 7 May 2020 14:00:33 -0500 Subject: [PATCH 2/2] mtd: Replace zero-length array with flexible-array The current codebase makes use of the zero-length array language extension to the C90 standard, but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99: struct foo { int stuff; struct boo array[]; }; By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertently introduced[3] to the codebase from now on. Also, notice that, dynamic memory allocations won't be affected by this change: "Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1] sizeof(flexible-array-member) triggers a warning because flexible array members have incomplete type[1]. There are some instances of code in which the sizeof operator is being incorrectly/erroneously applied to zero-length arrays and the result is zero. Such instances may be hiding some bugs. So, this work (flexible-array member conversions) will also help to get completely rid of those sorts of issues. This issue was found with the help of Coccinelle. [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by: Gustavo A. R. Silva Acked-by: Miquel Raynal Signed-off-by: Vignesh Raghavendra Link: https://lore.kernel.org/r/20200507190033.GA15215@embeddedor --- include/linux/mtd/cfi.h | 6 +++--- include/linux/mtd/qinfo.h | 2 +- 2 files changed, 4 insertions(+), 4 deletions(-) diff --git a/include/linux/mtd/cfi.h b/include/linux/mtd/cfi.h index c98a21108688..fd1ecb821106 100644 --- a/include/linux/mtd/cfi.h +++ b/include/linux/mtd/cfi.h @@ -138,7 +138,7 @@ struct cfi_ident { uint16_t InterfaceDesc; uint16_t MaxBufWriteSize; uint8_t NumEraseRegions; - uint32_t EraseRegionInfo[0]; /* Not host ordered */ + uint32_t EraseRegionInfo[]; /* Not host ordered */ } __packed; /* Extended Query Structure for both PRI and ALT */ @@ -165,7 +165,7 @@ struct cfi_pri_intelext { uint16_t ProtRegAddr; uint8_t FactProtRegSize; uint8_t UserProtRegSize; - uint8_t extra[0]; + uint8_t extra[]; } __packed; struct cfi_intelext_otpinfo { @@ -286,7 +286,7 @@ struct cfi_private { map_word sector_erase_cmd; unsigned long chipshift; /* Because they're of the same type */ const char *im_name; /* inter_module name for cmdset_setup */ - struct flchip chips[0]; /* per-chip data structure for each chip */ + struct flchip chips[]; /* per-chip data structure for each chip */ }; uint32_t cfi_build_cmd_addr(uint32_t cmd_ofs, diff --git a/include/linux/mtd/qinfo.h b/include/linux/mtd/qinfo.h index df5b9fddea16..2e3f43788d48 100644 --- a/include/linux/mtd/qinfo.h +++ b/include/linux/mtd/qinfo.h @@ -24,7 +24,7 @@ struct lpddr_private { struct qinfo_chip *qinfo; int numchips; unsigned long chipshift; - struct flchip chips[0]; + struct flchip chips[]; }; /* qinfo_query_info structure contains request information for