From aae8679b0ebcaa92f99c1c3cb0cd651594a43915 Mon Sep 17 00:00:00 2001 From: Thomas Tuttle Date: Thu, 5 Jun 2008 22:46:31 -0700 Subject: [PATCH] pagemap: fix bug in add_to_pagemap, require aligned-length reads of /proc/pid/pagemap Fix a bug in add_to_pagemap. Previously, since pm->out was a char *, put_user was only copying 1 byte of every PFN, resulting in the top 7 bytes of each PFN not being copied. By requiring that reads be a multiple of 8 bytes, I can make pm->out and pm->end u64*s instead of char*s, which makes put_user work properly, and also simplifies the logic in add_to_pagemap a bit. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Thomas Tuttle Cc: Matt Mackall Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/proc/task_mmu.c | 28 +++++++++------------------- 1 file changed, 9 insertions(+), 19 deletions(-) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 88717c0f941b..17403629e330 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -496,7 +496,7 @@ const struct file_operations proc_clear_refs_operations = { }; struct pagemapread { - char __user *out, *end; + u64 __user *out, *end; }; #define PM_ENTRY_BYTES sizeof(u64) @@ -519,21 +519,11 @@ struct pagemapread { static int add_to_pagemap(unsigned long addr, u64 pfn, struct pagemapread *pm) { - /* - * Make sure there's room in the buffer for an - * entire entry. Otherwise, only copy part of - * the pfn. - */ - if (pm->out + PM_ENTRY_BYTES >= pm->end) { - if (copy_to_user(pm->out, &pfn, pm->end - pm->out)) - return -EFAULT; - pm->out = pm->end; - return PM_END_OF_BUFFER; - } - if (put_user(pfn, pm->out)) return -EFAULT; - pm->out += PM_ENTRY_BYTES; + pm->out++; + if (pm->out >= pm->end) + return PM_END_OF_BUFFER; return 0; } @@ -634,7 +624,7 @@ static ssize_t pagemap_read(struct file *file, char __user *buf, ret = -EINVAL; /* file position must be aligned */ - if (*ppos % PM_ENTRY_BYTES) + if ((*ppos % PM_ENTRY_BYTES) || (count % PM_ENTRY_BYTES)) goto out_task; ret = 0; @@ -664,8 +654,8 @@ static ssize_t pagemap_read(struct file *file, char __user *buf, goto out_pages; } - pm.out = buf; - pm.end = buf + count; + pm.out = (u64 *)buf; + pm.end = (u64 *)(buf + count); if (!ptrace_may_attach(task)) { ret = -EIO; @@ -690,9 +680,9 @@ static ssize_t pagemap_read(struct file *file, char __user *buf, if (ret == PM_END_OF_BUFFER) ret = 0; /* don't need mmap_sem for these, but this looks cleaner */ - *ppos += pm.out - buf; + *ppos += (char *)pm.out - buf; if (!ret) - ret = pm.out - buf; + ret = (char *)pm.out - buf; } out_pages: -- 2.20.1