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Peter Anvin" Subject: [PATCH -tip v2 2/2] x86/ptrace: Use unsigned short for segment values in get_segment_reg() Date: Wed, 8 Apr 2026 10:22:12 +0200 Message-ID: <20260408082814.60213-2-ubizjak@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260408082814.60213-1-ubizjak@gmail.com> References: <20260408082814.60213-1-ubizjak@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Change the temporary variable in get_segment_reg() from unsigned int to unsigned short to match the function’s return type, making the 16-bit semantics explicit instead of relying on implicit truncation. Also restructure the GS handling for x86_32 to make the special case explicit and easier to follow. This clarifies the control flow and makes the 16-bit semantics explicit without changing behavior. No functional change intended. Signed-off-by: Uros Bizjak Acked-by: Oleg Nesterov Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: Dave Hansen Cc: "H. Peter Anvin" --- v2: New patch. --- arch/x86/kernel/ptrace.c | 24 +++++++++--------------- 1 file changed, 9 insertions(+), 15 deletions(-) diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c index 4cb00aa0645f..58e09a764bcf 100644 --- a/arch/x86/kernel/ptrace.c +++ b/arch/x86/kernel/ptrace.c @@ -182,19 +182,16 @@ static unsigned long *pt_regs_access(struct pt_regs *regs, unsigned long regno) static u16 get_segment_reg(struct task_struct *task, unsigned long offset) { - /* - * Returning the value truncates it to 16 bits. - */ - unsigned int retval; - if (offset != offsetof(struct user_regs_struct, gs)) - retval = *pt_regs_access(task_pt_regs(task), offset); - else { - if (task == current) + unsigned short retval; + + if (offset == offsetof(struct user_regs_struct, gs)) { + if (task == current) { savesegment(gs, retval); - else - retval = task->thread.gs; + return retval; + } + return task->thread.gs; } - return retval; + return *pt_regs_access(task_pt_regs(task), offset); } static int set_segment_reg(struct task_struct *task, @@ -248,10 +245,7 @@ static unsigned long *pt_regs_access(struct pt_regs *regs, unsigned long offset) static u16 get_segment_reg(struct task_struct *task, unsigned long offset) { - /* - * Returning the value truncates it to 16 bits. - */ - unsigned int retval; + unsigned short retval; switch (offset) { case offsetof(struct user_regs_struct, fs): -- 2.53.0