diff options
author | Joerg Roedel <jroedel@suse.de> | 2020-09-07 15:15:09 +0200 |
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committer | Borislav Petkov <bp@suse.de> | 2020-09-07 19:45:24 +0200 |
commit | 172b75e56b08846e6fb07a88e5685ce4e24f4620 (patch) | |
tree | 93def6ef8018f5ad625cb03347893a7c3fddb667 /arch/x86/lib | |
parent | 05a2ae7c033ee30f25fbed3ceed549a5cac398a9 (diff) | |
download | linux-stable-172b75e56b08846e6fb07a88e5685ce4e24f4620.tar.gz linux-stable-172b75e56b08846e6fb07a88e5685ce4e24f4620.tar.bz2 linux-stable-172b75e56b08846e6fb07a88e5685ce4e24f4620.zip |
x86/umip: Factor out instruction fetch
Factor out the code to fetch the instruction from user-space to a helper
function.
No functional changes.
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200907131613.12703-9-joro@8bytes.org
Diffstat (limited to 'arch/x86/lib')
-rw-r--r-- | arch/x86/lib/insn-eval.c | 38 |
1 files changed, 38 insertions, 0 deletions
diff --git a/arch/x86/lib/insn-eval.c b/arch/x86/lib/insn-eval.c index 5e69603ff63f..947b7f1a0042 100644 --- a/arch/x86/lib/insn-eval.c +++ b/arch/x86/lib/insn-eval.c @@ -1367,3 +1367,41 @@ void __user *insn_get_addr_ref(struct insn *insn, struct pt_regs *regs) return (void __user *)-1L; } } + +/** + * insn_fetch_from_user() - Copy instruction bytes from user-space memory + * @regs: Structure with register values as seen when entering kernel mode + * @buf: Array to store the fetched instruction + * + * Gets the linear address of the instruction and copies the instruction bytes + * to the buf. + * + * Returns: + * + * Number of instruction bytes copied. + * + * 0 if nothing was copied. + */ +int insn_fetch_from_user(struct pt_regs *regs, unsigned char buf[MAX_INSN_SIZE]) +{ + unsigned long seg_base = 0; + int not_copied; + + /* + * If not in user-space long mode, a custom code segment could be in + * use. This is true in protected mode (if the process defined a local + * descriptor table), or virtual-8086 mode. In most of the cases + * seg_base will be zero as in USER_CS. + */ + if (!user_64bit_mode(regs)) { + seg_base = insn_get_seg_base(regs, INAT_SEG_REG_CS); + if (seg_base == -1L) + return 0; + } + + + not_copied = copy_from_user(buf, (void __user *)(seg_base + regs->ip), + MAX_INSN_SIZE); + + return MAX_INSN_SIZE - not_copied; +} |