Commit-ID: 2b8d34b1ece506a9bbd47b56d266ee020a0c65ac Gitweb: https://git.kernel.org/tip/2b8d34b1ece506a9bbd47b56d266ee020a0c65ac Author: Borislav Petkov <b...@suse.de> AuthorDate: Thu, 19 Jul 2018 15:32:42 +0200 Committer: Borislav Petkov <b...@suse.de> CommitDate: Mon, 19 Nov 2018 10:51:05 +0100
x86/microcode/AMD: Concentrate patch verification Add a verify_patch() function which tries to sanity-check many aspects of a microcode patch supplied by an outside container before attempting a load. Prepend all sub-functions' names which verify an aspect of a microcode patch with "__". Call it in verify_and_add_patch() *before* looking at the microcode header. Signed-off-by: Borislav Petkov <b...@suse.de> Cc: x...@kernel.org Link: https://lkml.kernel.org/r/20181107170218.7596-7...@alien8.de --- arch/x86/kernel/cpu/microcode/amd.c | 79 +++++++++++++++++++++++++------------ 1 file changed, 54 insertions(+), 25 deletions(-) diff --git a/arch/x86/kernel/cpu/microcode/amd.c b/arch/x86/kernel/cpu/microcode/amd.c index a94a15aacfe7..8f012a7f88c4 100644 --- a/arch/x86/kernel/cpu/microcode/amd.c +++ b/arch/x86/kernel/cpu/microcode/amd.c @@ -139,11 +139,15 @@ static bool verify_equivalence_table(const u8 *buf, size_t buf_size, bool early) * Check whether there is a valid, non-truncated microcode patch section at the * beginning of @buf of size @buf_size. Set @early to use this function in the * early path. + * + * On success, @sh_psize returns the patch size according to the section header, + * to the caller. */ -static bool verify_patch_section(const u8 *buf, size_t buf_size, bool early) +static bool +__verify_patch_section(const u8 *buf, size_t buf_size, u32 *sh_psize, bool early) { + u32 p_type, p_size; const u32 *hdr; - u32 patch_type, patch_size; if (buf_size < SECTION_HDR_SIZE) { if (!early) @@ -153,24 +157,26 @@ static bool verify_patch_section(const u8 *buf, size_t buf_size, bool early) } hdr = (const u32 *)buf; - patch_type = hdr[0]; - patch_size = hdr[1]; + p_type = hdr[0]; + p_size = hdr[1]; - if (patch_type != UCODE_UCODE_TYPE) { + if (p_type != UCODE_UCODE_TYPE) { if (!early) pr_debug("Invalid type field (0x%x) in container file section header.\n", - patch_type); + p_type); return false; } - if (patch_size < sizeof(struct microcode_header_amd)) { + if (p_size < sizeof(struct microcode_header_amd)) { if (!early) - pr_debug("Patch of size %u too short.\n", patch_size); + pr_debug("Patch of size %u too short.\n", p_size); return false; } + *sh_psize = p_size; + return true; } @@ -181,7 +187,7 @@ static bool verify_patch_section(const u8 *buf, size_t buf_size, bool early) * header. */ static unsigned int -verify_patch_size(u8 family, u32 sh_psize, unsigned int buf_size) +__verify_patch_size(u8 family, u32 sh_psize, unsigned int buf_size) { u32 max_size; @@ -212,6 +218,34 @@ verify_patch_size(u8 family, u32 sh_psize, unsigned int buf_size) return sh_psize; } +static unsigned int +verify_patch(u8 family, const u8 *buf, unsigned int buf_size, bool early) +{ + u32 sh_psize; + + if (!__verify_patch_section(buf, buf_size, &sh_psize, early)) + return 0; + /* + * The section header length is not included in this indicated size + * but is present in the leftover file length so we need to subtract + * it before passing this value to the function below. + */ + buf_size -= SECTION_HDR_SIZE; + + /* + * Check if the remaining buffer is big enough to contain a patch of + * size sh_psize, as the section claims. + */ + if (buf_size < sh_psize) { + if (!early) + pr_debug("Patch of size %u truncated.\n", sh_psize); + + return 0; + } + + return __verify_patch_size(family, sh_psize, buf_size); +} + /* * This scans the ucode blob for the proper container as we can have multiple * containers glued together. Returns the equivalence ID from the equivalence @@ -687,7 +721,7 @@ static void cleanup(void) } /* - * We return the current size even if some of the checks failed so that + * Return a non-negative value even if some of the checks failed so that * we can skip over the next patch. If we return a negative value, we * signal a grave error like a memory allocation has failed and the * driver cannot continue functioning normally. In such cases, we tear @@ -695,14 +729,20 @@ static void cleanup(void) */ static int verify_and_add_patch(u8 family, u8 *fw, unsigned int leftover) { - unsigned int sh_psize, crnt_size, ret; struct microcode_header_amd *mc_hdr; + unsigned int patch_size, crnt_size; struct ucode_patch *patch; u32 proc_fam; u16 proc_id; - sh_psize = *(u32 *)(fw + 4); - crnt_size = sh_psize + SECTION_HDR_SIZE; + patch_size = verify_patch(family, fw, leftover, false); + if (!patch_size) { + pr_debug("Patch size mismatch.\n"); + return 1; + } + + /* If initial rough pokes pass, we can start looking at the header. */ + crnt_size = patch_size + SECTION_HDR_SIZE; mc_hdr = (struct microcode_header_amd *)(fw + SECTION_HDR_SIZE); proc_id = mc_hdr->processor_rev_id; @@ -723,24 +763,13 @@ static int verify_and_add_patch(u8 family, u8 *fw, unsigned int leftover) return crnt_size; } - /* - * The section header length is not included in this indicated size - * but is present in the leftover file length so we need to subtract - * it before passing this value to the function below. - */ - ret = verify_patch_size(family, sh_psize, leftover - SECTION_HDR_SIZE); - if (!ret) { - pr_err("Patch-ID 0x%08x: size mismatch.\n", mc_hdr->patch_id); - return crnt_size; - } - patch = kzalloc(sizeof(*patch), GFP_KERNEL); if (!patch) { pr_err("Patch allocation failure.\n"); return -EINVAL; } - patch->data = kmemdup(fw + SECTION_HDR_SIZE, sh_psize, GFP_KERNEL); + patch->data = kmemdup(fw + SECTION_HDR_SIZE, patch_size, GFP_KERNEL); if (!patch->data) { pr_err("Patch data allocation failure.\n"); kfree(patch);
